I'm having a problem with my '94 Deville 4.9L engine 70k miles that I hope someone can help with.
First symptom: On startup the engine revs high (like 2500). It quickly drops to around 1200 by the time "Monitored systems ok" goes away and is down to normal idle quickly after that
Second symptom: Upon slowing the car is fighting to keep the engine speed up. If at
40mph I put it in neutral the rpm goes to 1800 and holds there until the speedometer gets to 0. Once the speedometer gets to 0 it drops back to a steady idle at 650.I have no codes. I have reset the computer by disconnecting the battery overnight and done the idle relearn per the FSM. Now it is worse than it was before!
I have checked for vacuum leaks and found nothing. Don't believe it is a vacuum problem since the engine will idle perfectly when the computer will let it. Help??
Steve B.