Cadillac Repair: 1994 self propeller, consistant basis, speed control

Question
i just got this caddy and it had an transmission change..now it seems to want to take a high idle most of the time..rpms is around 12 to 1500 on a consistant basis.does not exceed that on its own..just as explained self propeled..we can start here if you like.. you got any ideas what could be potential problem

Answer
IS or HAS the CHECK ENGINE light ever illuminated on the dash ?.

If it HAS, What fault CODES are you getting from the computer ?.

Possible faults:

Faulty ISC Iidle speed control motor).

Faulty TPS (throttle Speed Control motor)

IDLE SPEED RE-LEARN process not performed after transmission swap.