I have a 1995 vw jetta, and it seems that when i first start the car up after having been cold it will run like a champ. but as soon as it gets warmed up a little, it will not have any power upon acceleration, and in lower rpm's it will seem to stumble. check engine light on, and if the rpm's get above 4 thousand it seems to do a little better.

Optional Information: 1995 Volkswagen jetta 2.0
Already Tried:
replacing plugs wires cap rotor fuel filter temp sensors