I have an 87 van, I expect it is not too different than a 86 truck.

All that follows assumes I am right about that:

The "small 'boxes'" are likely solenoids valves--specifically EGR & upstream/downstream smog solenoid valves,

Neither of them are critical for getting your engine running correctly.

You probably have an idle stop solenoid, and do not have a curb idle screw (apart from the one on the solenoid).

Much of what you describe may be as simple as once it comes off the fast idle cam, nothing is holding the throttle open. (..along with a bunch of vacuum leaks causing a lean condition that does not like you opening the throttle)

To keep things simple you can cap off all the ports on the carb except PCV (hook it up properly) and bowl vent.

You can cap off all the ports on the vacuum tree on the #6 runner but one, and run a hose to the ESA vacuum port. (Assuming you already confirmed it holds vacuum.)

This will eliminate vacuum hose and device leaks as variables.

Check for current at the idle solenoid when it is running. If there is none, disconnect the pigtail and jumper the solenoid directly to the battery (some solenoids have 2 wires--one is to a contact that grounds on the carburetor. Make sure its the one to the solenoid coil) and watch to see if the solenoid plunger moves out, and back in when you remove the jumper.

If it moves then it works, and it is probably free enough of crud and corrosion to adjust without stripping the screw. IIRC it adjusts with a 1/8" Allen wrench at the end furthest from the carb. You may be able to get it to idle off fast idle cam, even if the idle is way higher than spec. This may let you keep it running long enough to check other things.

If you can get it to stay idling, you can proceed to check for vacuum leaks at the intake manifold gasket, intake air sensor, vacuum tree base, EGR gasket, and carb base gaskets.

If there is anything at all wrong with the lean burn, I strongly recommend replacing it with HEI, but before you do, you should make sure that the stuff the conversion is not going to replace is working reasonably well, otherwise you are just adding variables to the problem.

It is entirely possible that plugging off the vacuum lines/devices as above may greatly improve idle by itself (by virtue of eliminating vacuum leaks).

Even if your ESA does not hold vacuum, you can just leave it disconnected and fully plug the vacuum tree. It only really just acts like a vacuum pod. You should be able to achieve decent idle without it. (You are getting spark, so the ignition control aspect is working--more or less)

If you get it to idle ok with the the lean burn and emissions stuff bypassed, then it will likely be fine after an HEI conversion. (You can restore those systems after the conversion--especially the purge canister. If you want to run the EGR the 87 EGR amplifier and valve will work with the EGR ports on an earlier carb. The smog pump still works without the vacuum lines and solenoid valve, it just doesn't switch from upstream to downstream).

None of this does anything for a bad carburetor, but I strongly suspect the shiny carb you described was the PO's last bad guess as to what was wrong.

That, in and of itself, introduces a whole other variable: crappy part store rebuilds.

It is always possible to run an older carb (i.e. good HEI candidate) with the lean burn system in place as baby steps to a conversion. (i.e don't wast time and money rebuilding the lean burn carb. Get one from a pre-lean burn slant 6 truck and rebuild that one. Same kit price. Same amount of time spent rebuilding it. You just have to spend $20-$50 on a rebuildable core.)

Wow, I am so gratified at the valuable response to my problems--it's clear you have a wealth of information, backed up by a lot of experience/patience. Thank you all so very much!
I am learning kinda slowly--I am now thinking I may need to dump this smog era carb and find one that can "stand alone". Could I continue with my current distributor? It seems to be working well for the moment--or do I need another distributor to go with a simpler, older carb? As you can see you are dealing with a guy with limited knowlege. I can rebuild Honda Goldwing carbs with good success, you'd think a single bbl carb wouldn't be so perplexing.
Here's what I did recently: I had an 'expert' install a carb kit on the lean-burn carb. He found the choke pull-off didn't work so he got one and installed it. Total price: $180.
I installed the carb and the engine started up fine but wouldn't idle, nor would the choke close. The accel pump is now squirting so I can get the engine to run by manipulating the throttle. It ran bad til it gained some temperature, then it ran pretty well, it just wouldn't idle. I could drive it around just fine because of my skills driving vehicles that won't idle. The motor sounds good, trans shifts fine, all lights and guages work great. I still think this is a worthy project, it just resists all my efforts to get usable drivability.

So a knowlegable friend tried to help me--he is well versed on all chevys, he is talented in tune-ups, and he fiddled with all my rods, links, adj screws trying to make it idle. After quite a lot of sweating, cussing, he gave up in disgust saying nothing he knows about carbs seems to work on this one.
So I am now thinking I may need to get an earlier pre-smog carb and dump ALL the lean burn aparatus.
Will a Valiant carb from the '60's work on my motor? Will throttle linkages match up? I'd gladly use a manual choke--what carb should I be looking for?
There are remanufactured carbs online--what should I ask for?

Smog era is not your problem.

Lean burn era may be.

60's and early 70's carbs have no provisions for some equipment on your truck

Lean burn carbs and distributors have no mechanical means for vacuum advance.

The distributors have no vac pod, and the carbs have no ported vacuum to operate a vac pod.

Lean burn advance is electronic and gets it's vacuum signal un-ported directly from the manifold.

You can run a late 70's Holley 1945 w/out lean burn with the lean burn ignition in place temporarily.

Optimally you would want to use a rebuild kit for a truck as the power valve is supposed to be different, but I have never seen any real evidence of this (most kits I've bought are listed for cars and trucks of the same year, and only have one power valve--or just the spring in the package.)


Proceed as I had recommended re. make sure ESA holds vacuum, plug all vacuum ports, get PCV working 100%, check for manifold leaks in the areas I mentioned, and let us know where you are.

You need to adjust or replace your choke. The correct choke for your truck should be electronic assist.

Is the wire plugged into anything? Is there power going to it?

From the factory the choke is plugged into a modulator--a 1" round disk attached to the head by a bracket on one of the hoist bolt holes. The modulator has (2) 1/4" male spade terminals. The other wire goes to the oil pressure switch.

With the key in run, power goes to the oil pressure switch. When oil pressure meets some threshold, power continues to the modulator.

I don't know what the modulator does, but eventually power goes from it to the choke.

If your choke doesn't close, it could just be poor adjustment by the re-builder binding and holding it open.

Disconnect the rod from the choke, open the throttle, and try to close the choke butterfly by hand. If you can't, your pull-off linkage may be badly out of adjustment or possibly the wrong one. The linkage from the fast idle cam may also be way out of adjustment or installed wrong.

Well it is not likely to run right with all those lines broken, so yes, replace them all as a first step towards fixing.