Well, when the engine is still cold, it won't accelerate past 3000rpms without sputtering wildly. That'll persist until it shifts, then do it again once it gets to 3000rpms. Once the engine warms, that problem eases a bit and is replaced by power loss and popping in the exhaust. And when I let off the accelerator, it backfires. I've already replaced the spark plugs, fuel filter, catalytic converter, map sensor and EGR valve. I'm at a loss here... any help would be appreciated.

 

sighs...lets see...have you checked your injectors yet? what about ecu? are you running stock one or replaced it? Im still thinking...

 

most likly a dizzy issue or coil

 

Definatly sounds like a Distributor arcing out.

 

I'd clean the EGR passage and see where you're at afterwards. I had a huge problem with drive-ability until I poured Seafoam down the EGR opening and let it soak for a couple hrs, then when and revved it until all the soot and crap ended up in my driveway. No problems since. My symptoms were also sputtering, backfiring and power loss and a rev limit of about 3k

 

def worth a try..didnt think of that, but now that you mention it that might just be the issue.

 

To me, sputtering/popping sounds like a fuel issue. Like not getting enough fuel issue. If the mixture is too lean, it will burn more slowly, slow enough that it will still be burning as the exhaust valve opens and the burning mixture is expelled out the exhaust. This is commonly refered to as a "backfire" but is more accurately called "afterfire"; fire that comes out AFTER the combustion event. Backfire refers to fire coming out the intake "backwards". Folks that have tuned their own cars know that point of about 16-17 afr when the engine starts to break up because its too lean. Some more info about the car history would help, like is this a stock car or has it been modded/tuned/etc? A lack of fuel will def. cause low power and sputtering, esp when the engine is cold, as a cold engine needs about 30% more fuel than one that has been warmed up.
GL and hope this helps
Mike

 

The inverse is true as well, too much fuel can cause "backfire" and sputtering.