I've got a 91 305 5speed camaro with roughly 145k on it. Stock except for the open element air filter and the cat/air/emissions are gone. It's had a full tune-up along with a new MAP, IAC, TPS, O2, PCV & fuel filter. Just recently I put on a new timing chain as well. Timing is set at 2° btdc and that's all I can think of right now. All of this solved a portion of it's running issues except a couple.

When the car is warm or cold and coasting to a stop, clutch is pressed in, the engine begins to hunt up and down from 900 up to 1400 rpms (as according to the tach) and then idles normal once the car is 5-0mph. Once warm, it still hunts but not as high up in the rpms. Every once in awhile also, the car also has a serious lack of what little power it has (i.e. press gas to go faster, no go but, makes all the noises like it's trying to)
All vacuum lines appear to be in good shape and have a good fit which is leading me to believe that the EGR (looks to be original) is not working like it should.
My other guesses are the fuel pump doesn't have much milage left in it or, bad PS pressure switch <-(that wouldn't cause hesitation though would it ?)

Am I on the right track or way off base here ? Any thoughts, information, or advice is appreciated.

 

It could be a lot of things with that kind of mileage. You said you have new plugs and wires? I would check out the fuel pump and egr to make sure that they are working properly. You may also have a clogged fuel filter or dirty injectors. Change your fuel filter and watch your injectors spray. Do they drip, or spit? If so they could be malfunctioning or dirty.

 

Thanks for the reply Shifty.
The fuel filter is 'fairly new' but will be changed this weekend with the oil. I may go ahead and get a new EGR if I've got the scratch for it. I'll give everything else a once over and see what happens.

 

Before you just change the EGR make sure it has the right vacuum and opens and closes. I can't remeber off hand how to do that but if you have a vacuum gage it is pretty straight forward. If anything, take it off and spray a bunch of carb cleaner in it and clean it out real well. Sometimes they hang wide open and do not close because of some gunk. Then again it may be shot. It is a just a simple way to see if you have to spend the money or not.

 

I had a few spare moments last night and hooked up my Mityvac to the EGR to see if it was holding anything (I assume the EGR should hold a little vacuum or at least try). Well, it does nothing. 0 vac hold, build or even attempt so, I unhooked the vac. line from the solenoid (solinoid ? never can remember that..) and plugged it on the assumption that it is just a vacuum leak when it opens.
This morning I had to beat the mule to get onto the "expressway" and I believe this is the 1st time my p.o.s. has gotten over 4k rpm w/o falling absolutely flat on it's face.
It still is having the hunt issue but now it's random (i.e. sometimes drop & raise, somtimes not) and the hesitation is a little more subtle.
Thanks again for the extra brainpower Shifty.