Ok here is the issue. I have a 350tpi and she runs great as can be. Here is what the issue is.

When i start her up there is no issue, just runs fine. When she get warm she starts to have hessitation issues. The tach jumps from 600 -400rpm and then the lights dim a bit when i have them on. When i do get on the car it goes just fine. Id does it in D and N aswell.

It does have a brand new powermaster alternator and a optima redtop battery. The car gets warm in no time and the temp gauge stays at normal.

I checked for vac leaks and didnt find anything. I got no codes when i ran them aswell.

Here is what i was thinking..
egr?
bad plug or wire?
Sensor somewhere?
I did think maybe a o2 or clogged cat but id knoticed that.
fuel pump going or tired? or bad injector?

Im running 93 octane and put in dry gas so im lost.

Thanks for any helpful suggestions

 

cleaned the IAC valve lately?
Just a thought.I know they sometimes get carboned up and start acting screwy or just plain go bad with no warning.