Made a home-made smoke tester, hooked it to the manifold, and smoke came out of the side of the intake where thr throttle shaft hooks to the throttle cable that opens the throttle butterfly. Could this cause rough idle? How the heck do i fix it? Thanks!

The pic came out sideways, sorry bout that.

 

Does the truck have a maf? If no, most likely it will just idle high. If yes it will cause all kinda weird funky things.

 

MAF sensors didn't come into play until 1996 with the SCFI motor. Without a MAF sensor, a slight leak around the throttle shaft should have no impact on engine performance and certainly would not cause a rough idle.

 

No MAF, just MAP (new). I thought(could be wrong) that any vacuum "intake manifold envelope" leak was bad. More air = leaner = more fuel called for by computer = etc. There's lots of threads on TBI throttle shaft vacuum leaks, but cant find any on CPI's.

 

Pulled the spring and little plastic bushing back and re-smoked. It started coming out all around the throttle plate shaft. Looks like a little red bushing or grommet, but I can't find it on AC Delco or GM Parts. Is it replaceable.

 

new upper manifold sadly, junkyard is the choice.

 

Try backyard fixing it with a small O-ring and some lithium grease... Im betting that small bushing is just worn out and a simple backyard fix may get you going again. I dont think that small leak is going to give you a rough idle on OBD1 though sadly.

 

Are the first gen (obd1) not as sensitive to small vac leaks?

 

Used the dollar bill and tailpipe trick, never even hinted at sucking it in. Exhaust valve is off the list I hope.