My '00 SSei misses at approx 4,000rpm...can anybody tell me why and what I need to do to correct. This is when I am parked and idling! Thanks,

Mac

Thats your rev limiter kicking in and good thing. Reving a parked or neutral engine is not a good idea, with out load many things can rattle loose inside and uh oh.

Free revving your engine is not good for it, and should not be done. So, to protect the engine, GM programmed a rev limiter into the computer. That'* normal operation to keep you from doing damage.

Edit - And I was "this close" to beating out PDad with the answer.

Thanks...I can breath easier now!! And no this is not something I do all the time. Just did a couple of times to help blow out the crap build up using regular gas! Now that I put premium in it it appears to be running pretty good! Thanks again,

Mac

revving your engine, whether in gear or not, is not a good way to "blow out crap", if you would like to clean your valves and injectors, use a good quality fuel injector cleaner every 3k miles. otherwise you can run seafoam directly into your combustion chambers.

and yes, as said, revving under no load is an extremely bad idea, wastes fuel and is obnoxious.