I really, and I mean really hate to keep adding to this excellent thread, but I have a 98 GT bone stock except for a K&N. It has been stored for about 5 years, but I start it every 2 months and run it. When I put it away I was having this issue and am still having it after taking it for a short run last week. Believe me, I have google this for three years and read tons of info before posting anywhere. Seems to be so much conflicting info out there..so here we are!
It started back just before I stored it. No start or a very hard start, followed by poor idle, an intake backfire and then in would smooth out.I pulled the IAC cleaned it and that problem went away. What I had then and still have now is a great start and smooth idle but after driving it for 20 mins or so I start to get the cruising, part throttle missing, it happens around 1500-2000. If I take the auto trans
out of OD and run the RPM's up I don't see it so much, If I get on it, no hesitation at all !! looks rich in the rear-view mirror and it just doesn't seem to have the jump it did (65,000 now)
While driving it the other day I threw a code of 443, the "Canister Purge Sensor" I have one on order and expect it any day. However, its about 50/50 out there on the WWW that the sensor won't cause my stumble symptoms?? Will it?? I am going to try that first and check all lines and the PVC once again! I have a new IAC and again I read about 50/50 that it may cause the symptoms? Could it? very confusing.
New O2's..Cleaned the MAF with or course MAF cleaner, didn't work! The EGR seems to be moving okay but I have not pulled it off and cleaned it. Cleaned the throttle body. The plugs were new when I stored it bosch I think? and the wires and coil packs are original. The rich mix puzzle's me, but maybe it would make sense if I knew what was wrong.
Sorry for the repeat and the long post..Any ideas? could it be a combo of EGR, IAC and the purge sensor? Wires?? TPS? AGH!! don't have much money to try everything..love some input!