i have a 99 eclipse when i start the car the rpms rev up to about 2500 to 3000 and goes back down now to about 1500 in park and 1000 in drive now when i drive around acceleration is fine how ever when i brake the car revs up a few hundred rps like im accelerating and causes the car to jerk while im trying to stop and when i stop and put the car in park the car is at about 1800 rpms so i replaced the iac valve but that didnt fix the problem ive asked a few ppl what they think and they said i should replace the iac valve or the throttle position sensor ... is their anything else that could possible be goin on that needs to b fixed (check engine lite is not on) also is their a specific setting on the iacv or is it preset in the box

 

Could be that the throttle body needs to be cleaned and the plate is getting stuck

 

What engine do you have the 420a or 4g63?