acquired a 86 van that I am trying to revive and I noticed that it has a canister under the passenger floorboard with several vacuum lines that have at some point in time been plugged off. I believe its a evap can because of a small line going towards the rear but not for sure. my questions are do I really need this and will it effect my performance/ economy and if so how much

Yes, keep it. It helps with hot starts and improves fuel economy by trapping the fuel vapors that escape the carb when it sits. It has absolutely no negative impact on performance and a positive impact on economy.

alright then I can hook it all back up ... looks like its been unhooked along time well I know my grandfather bought it in 95 and I don't belie
ve he ever had the dog house out of it

...and You might want to install a transparent inline filter just to be sure that the canister is in good condition and not releasing any charcoal bits into the carb.

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"Hey, I like that paint job you got. What they call that--sorta a cross between Piss Yellow and Puke Green, ain't it?" -- Bob Falfa

There may be a small filter on the bottom of the cannister. If so, it should be replaced as well as a maintenance item.

I've never seen a vacuum filter but I will sure check out the can on my van to see if it has one and ask for the inline ones next time I am in Autozone

You'll need a regular fuel filter (oriented from canister to carb) and fuel line hose not vacuum hose to carry fuel vapor.
Like Reed said the pad at the bottom of the canister should also be replaced.

_________________
"Hey, I like that paint job you got. What they call that--sorta a cross between Piss Yellow and Puke Green, ain't it?" -- Bob Falfa

seems simple enough, can you get the pad at any auto parts store, this is all new to me, probably because most people would rather just unhook, plug off or just throw away anything like that. Shadetree mechanics

If you pull the pad and the charcoal pellets fall out, you'll need a new canister...the packing the charcoal is held in just doesn't hold up after 30 years....

-D.Idiot

about how do those cost and where would be the cheapest/best place to get one?