sturdybirdy

Hi there. I have a 1988 firebird formula, manual 5 speed tranny and a 305 h.o.
TBI injected engine. When it starts from cold, the idle will go to 2500 rpm and stay that way for quite a while(like choke sticking). Then will run ok but has a rough idle when warm and at a stop...it won't really quit but seems to not run on all 8 cylinders and rpm's drops below 450 then oscilates to 900 then back down again...engine will then hesitate when i give it gas. The engine temperature is descent but this only happens when engine is warmed up. I did change the IAC valve and I also changed the throttle body gasket because I detected a air leak(using the old carb cleaner trick). I am getting bad gas milage too.I am now a little stumped and wondering if the EGR valve is bad or maybe the O2 sensor...What do you think!!!

ex-x-fire

Disable the egr valve by plugging the vacuum hose that goes to the valve, drive it a couple of days to see if it acts up.