After warming up; while driving; when letting off accelerator, the RPMS stay up & descend very slowly; steadily pulling; vehicles has been sitting for 2 years, 97,000 original miles. Any ideas?

 

sounds to me that this vehicle is in need of a tune up I had similar problem with my 92 and after the tuneup it was running better

 

my 95 deville does it too, but not horribly, my ISC motor causes that

 

Condition is called sail on. Make sure throttle plate and bore is clean of carbon. Re-learn TPS and idle. See if that correct condition.

 

slowroll: you lost me; I am familiar with the old school vehicles, but modern stuff, I am lost.
I will look in the repair manual to see what that is.

Would carb cleaner clear up the problem if sprayed in that vicinity?

 

4.1-4.9l pfi and 93-95 northstar engines have learned tps and idle. "SAIL ON" is when car wont slow down when throttle is released. It will be caused when PCM loses 12v (KAM) either from dead battery or disconnecting battery or PCM. Or if min air rate/tps is out of adjustment. Northstar has extra steps. Refer to the following thread

http://www.cadillacforum.com/m_18624..._2/key_/tm.htm

Request TSBs T93-44 and 31-60-06A from local dealer they pertain to this concern.

 

I noticed that the ISC motor delays the accelerator from returning to the idle position. It returns in increments of 1/16" causing the RPMs to stay high.

Slowroll: could the ISC be the problem or would the carbon build up cause the ISC from closing up.

Thanks Tater