Not returning to idle

[vtmecheng]

I have a '95 S10 pickup, 4.3 Z, 5 spd manual, manual eng. 4X4. For probably 3 years now the truck has had a problem with returning to idle, especialy when cold. I start off in 1st gear and when shifting to 2nd the idle will either not drop at all or even increase while the clutch is in (no gas on obviously) and it will do this through all the gears. It doens't do this once hot but the rpm's still seem to decrease slowly. Here is a list of everything I have replaced: Spark plugs, wires, cap, rotor, O2 sensor, IAC valve, and TPS. I think the only thing left for me to try is the EGR valve but I didn't think I could cause something like this. Thanks everyone in advance for the help.

[Fractured1]

Not sure this would help but have you cleared your computer, pulled the neg. wire off the battery for 10 min or so...I think there is a learning process one the power is restored...may or may not help but I would give it a shot...Good Luck

[vtmecheng]

Yeah, disconnect the battery whenever I change an electrical component, like the O2 sensor or TPS. Thank you though.

[rlith]

Check the IAC, and check your vac hoses... Pull each hose 1 by 1 and check with pressure or vac. Also check your injector spray and the tbi gasket.

[vtmecheng]

I already replaced the IAC, it was the first thing I figured would be wrong. TBI gasket is good because I put a TBI spacer on and replaced all gaskets in doing so (the problem was present before the spacer so it isn't that). The injector spray is a nice even mist so I don't think that is a problem either. I will check all the vac. hoses tonight though. Do you know if the EGR valve could cause this? Thanks

[rlith]

It's possible... You can pull it and clean it (carb cleaner and a wire brush, make sure the pintle is moving freely)

[OverBoardProject]

I would imagine that you looked at the simplest possibility, and made sure that the throttle cable isn't a little gummed up

[vtmecheng]

Yeah, the butterfly valve in the throttle body is closing fully. Thanks though.

[OverBoardProject]

I really can't see the egr valve causing these problems unless there is a vacume leak through it.

It also couldn't have been the Spark plugs, wires, cap, rotor... but it's always a good idea to change them from time to time anyways.

It is probably some sort of vacume leak, like rlith said. Sprayng wd40 on every possible vacume leak will usually show you where it's at.

Good luck

[vtmecheng]

I just wanted to give a quick run though of all the new parts on my engine. Thanks for the help, looks like fun with vacuum line for me.