The truck is an '87 with the 22R. Decided to do alittle checking around today under the air cleaner. Came across this thing? Notice how it's unplugged? See the vacuum line in the other picture with the screw stuck in it? This is something that the previous owner apparently bypassed.

Out of curiosity, I hooked it up. When I start the truck, it idles like crap.....and blows black smoke from the tailpipe. When I disconnect it again, the truck runs fine again. I'm guessing this little diaphram thingy isn't doing its job correctly? <img src="/forums/images/graemlins/lol.gif" alt="" /> My question is. What it is? What is it supposed to do?