Hello everybody. I have been experiencing what I beleive to be a miss in my engine. The car only does this on ocassion, and usually after it is warmed up. The engine idles under 1000 rpms, then rpms will dip down slighty, and jump up breifly. This happens very quickly, but if your foot isn't firmly on the pedal, the car will lerch forward. You can also feel an odd operating condition intermitently 50-up, where the car will surge almost, but it feels as if the engine is missing. Then it will stop. The rpms do not noticably shift when this occurs. Does this sound like engine misfire? Vaccum leak maybe? Or something else?

The first question I'd ask is if you pulled your MAF screen out or not.

After you answer that, we need to know when the last FULL tuneup was. There'* a ton of things it could be, but the best place to start is the normal stuff. Plugs/wires, fuel filter, air filter, PCV valve, and O2 sensor (if you don't know how old it is). It could even be the MAF sensor, but not as likely.

I had a similar problem with my first replacement O2 sensor (a Bosch, wouldn't you know) and it cleared up after putting an AC Delco in. I don't think my problem was as severe as yours, but it sounds similar.

Well, I have done a lot of that trying to remedy the problem already. The plugs, wires, pvc valve, air fliter, fuel filter, have all been replaced. I just replaced the catalytic converter. I read a post where someone had this problem and it was the EGR valve? I thought about replacing that. And I am not quite shure what the MAF screen is? Where on the car is that located, and what does it effect? This happens intermitently. If you stay at a constant pace anywhere from 50-up, it will run ok for a while, then suddenly there is a noticeable skip, or miss almost in the engine, repeated a few times, almost exactly 4 seconds or so apart, and then its fine for a while. Of course then it still will occasionally have an RPM fluctuation during normal idle. This is exreme though, cause it sinks down to like 500, and then back up to 1300, and then back to where it sits normally at about 900-1000. Any more ideas? I do want to check on this screen

I'm going to try cleaning the mass airflow sensor by removing it and cleaning with brake cleaner. I also cannot seem to fix this.

Well, what do you all think of the EGR valve in question? could it do what I was explaining before if its malfunctioning. Mine has a digital EGR, and I have seen some info. on the old style EGR becoming corroded and causing this in the car. Can a digital EGR do this too?

I think its kinda funny how a buddy of mine at college cleaned my MAF sensor because he was sure that was what was wrong with my car. It had all kinda dark residue on it. I told him he would have to buy me a new one if he farked it up but he sprayed it anyway with some carb cleaner and it never hurt it one bit. Go figure. After that it was shiny like it was brand new.