91 eclipse gs automatic throttle problem

Ok I just got this car. When it starts it jumps to 3000 rpms, then it goes down to 1000 then it goes up and down between 1000 and 1500 so long as its in park or nuetral. When I put it into drive or reverse it idles fine. If the car runs for a while it stops all together. I have cleaned the throttle sensor already. Someone told me to change it and the map sensor, but the screw on the bottom of the map sensor is a pain to get to, plus I don't even know if thats the problem. the car runs good other than that. Also very rarely but sometimes when Im slowing down the it will do the idle thing in drive but it only does it like once. Thanks for any help.

Sounds like the problem I used to have with my old Firebird... I changed the PCV valve, cleaned my air filter and changed my fuel filter and the problem seemed to disappear... So I have no clue what actually solved it, but I got it solved somehow... Just give the car a well rounded tune up and see if that helps anything. If not, it won't hurt anything to have a tune up for once you do get the problem solved. :2cents:

Anyone got any other ideas? Ive cleaned the pcv valve and air filter already

What engine?? Is it turbo?

Check Idle Speed Control

Look at autozone.com for repair manual

Does the 1991 have a IAC ? If so , remove / clean / test again.