OK I've had nothing but bad luck. I blew the first motor. Replaced it now its running really bad. It wouldnt idle below 1000. I later found out the knock sensor was bad took old one off other motor relocated it and fixed that. now when i stop after being on the highway 70+mph it will rev to 1100+ then slowly drop to 750. if im going down the highway at 70 somtimes the rpms are at 2900 but sometimes they are at 3200+ and if i let off the gas an then give it gas the car jerks really bad. In nuetral i can take it to 2000rpms and it drops to 1500 then to 2000 and back over and over as long as i hold the gas still. Its a 90 NA 2+0 Auto And I have already checked codes and none
parts I changed
Crank angle sensor
TPS
FPR
Air regulator
Idle air controller
AAC valve
temp sensor
fuel filter
knock sensor