ok. i was pulling my manifolds off today to clean them up a bit in the inside with a dremel, and to paint them. so im putting them back on and i messed around and tighten one to much. bam it cracked the lower intake manifold. so i put the parts all back together and started it up and it wouldnt hold a idle for nothing. my friend messed with the screw that is on the back of the tb by the gas cable. i think it is the idle cam adjustment or something. but he loosend it up. what im tryin to figure out is why is it still not idling. i have put another lower intake manifold from a 87 gxl and sealed it well with black rtv and checked almost everything. but its still a no go. the thing is it will run good if i give it 3/4 gas or more. when im giving it like 10-40 percent gas or so. it will poop and studder,shake. what do u think this is guys. im really stumped. thanks

 

bump. someone must know something

 

not enough info might want to buy a shop manual
good luck

 

I would pull the throttle body off and double check the setting of the idle and the cold idle. Also there is a screw on top of the throttle body right in the middle that screwing out will increase the idle. I would think a vacuume leak would make it Idle higher.

Could be you had a leak and your work fixed it. Now you need to reset everything to factory settings.