[Jim Curry]

Hello all, I have a 94 Impala SS, stock with cold air Intake. -125K miles, runs excellent except randomly after start up (usually 2nd start of the day) for a few minutes there is no power, stumbles and sometimes manifold backfires. I have changed plugs, wires, EGR, cleaned Throttle body, added air foil, cleaned MAF sensor, new fuel filter and a complete scan which showed nothing and no codes. The last thing I’m guessing to check would be the fuel pump as if I have time to let it idle a few moments it seems better.
any ideas?

I’ve been pursuing this site for a couple years now, since I was lucky enough to find a 94 bone stock SS, absolutely love it and has become my daily driver. I just signed up as a member, this site is amazing with so much experience knowledge and good folks, it’s very much appreciated.

Thanks, Jim

 

[96 Black]

It isn't really 'throwing parts at it' as long as everything you've change so far on that quarter-century old bucket has been an original part. That way, it's just considered long overdue scheduled periodic maintenance, and perfectly called for since it sounds like you're not the original owner to know the history.

Things associated with changes of operation after coming up to temperature include ignition coil and ICModule which I don't see on your list, and you haven't mentioned the old 'shake TS outta every wire and harness you can find under the hood when hot' for loose connections, baked wiring and bad grounds. First things first and do the fuel pressure test most soonly.

 

[Jim Curry]

I appreciate your response, I will certainly follow your recommendations, I do know that it was due for the plugs and wires. I was going to buy new 02 sensors and the service mgr said exactly what you said, “dont just throw parts at it”, good advice.