Appealing to carb experts: 1987 caravan with carb 2.2L engine. Carb is holley 5220.

I attempted to cut back on idle mixture a bit and this works, rewarded me with jump in idle speed and I had to close down throttle to bring back 900rpm but this is not great when in gear, idle rpm drop low that is rougher and light miss. I think I have new respect that I really have throttle shafts leaks even it's not giving me too much issues with this?
I can see a reason carb needs throttle blade ever slightly open that means need tight throttle shaft bushing clearances to work right?

Background:
Last June, I replaced the head with correct camshaft to fit better with ignition curve built into antique spark control computer. Another reason to do so because head is cracked and is newer than van with galled 3rd cam journal and off by 4 degrees. Got that done and chased down last vacuum leak on EGR system. MUCH better in horse-power department yet MPG stubbronly stuck at 13 MPG and idle is worse as explained above.

Cheers, Wizard

You will have better luck with your Caravan questions on one of the many FWD Mopar forums.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Thanks Dan, the issue is not very many people are that expert on carbed mopar especially holley 5220. The one I frequent allpar.com is mostly into TBI and MPFI, some occasional people do pop up then and now with carb 2.2 and 2.6 other than that that it. The other one turbododge.com have one section but only one member know barely enough about 5220 but does lot of mods to 2.2.

Here's my problem especially the carb.

Is there decent forum like here and allpar for example. turbododge.com is barely civiled but heavy on building stuff and throwing together stuff and some knowledge. Here is awesome.

Cheers, Wizard