newbie here...2003 Lancer question
 

I been trying to figure out why the idle goes fast after awhile of driving. When I stop it goes to 1500RPMs in Drive...and when I neutral or park it..idle jumps to 2500. I changed the ACV and the 2 oxygen sensors that go front and back of cat conv. Need help

First of all note I'm a weekend tinkerer and not an expert by no means.

Try the simple things first.

1. Remove one battery cable for a minimum 30 mins. Re-attach, start the car and put it in drive with the car in drive while holding the brake pedal. This will reset the system and let it reset things like idle rpms.

2. Remove any air pockets in the cooling system:

Remove the radiator cap
Park the car with the nose uphill .. let it warm to normal
Put it on high heat .. squeeze the upper radiator hose .. look for bubbles

3. There might be an air bleed screw on the inlet manifold. Bleed it.

4. You might have a BISS screw that it out of adjusment.

5. You might have a vacuum leak.

I'm sure others will chime in with other better suggestions. Just trying to help. Have a great holiday weekend. Idle should be around 750 rpm normally on most of the cars I've owned.

Do you have a check engine light on? Could be a vacuum leak or possible bad isc.