Service Engine Soon

[Hoytman]

1999 STS with a P0102 fault code. Replaced the Mass Air Meter and the car still acts the same and the code returns.
-Slight rough idle
-code P0102 even with new MAF
-Service light on(car seems to only run with the service light on)
(if code is cleared the car starts and stalls until it
begins to run in limp mode & then it wil idle)
Seems like there is more going on here than just the MAF code but the car will run down the road okay with the service engine light on.
No obvious underhood problems(vacuum leaks etc..) just started acting up recently. Nice car with only 53k miles.
I'm scratching my head on this one..??

[M.A.C]

Did you check for vacuum leaks? What about the EGR valve to see if it's stuck open? It sounds like a vacuum problem--just my 2 cents. I could be totally wrong?

[ctesla]

premium being used?
it does sound vacuum related; EGR, or cat possibly.
does GM have a TSB on the 99s?