ok when my car is warm at regular operation temperature, and u let it idle it sucks if u leave the headlights off and let it idle the idle goes up and down then it turns off by itself and when, u have the headlights on the idle goes up to like 1100 rpm and down to like 250rpm and just keeps doing that i dont know wat to do its a D15b7 engine. I want to keep the car running right till this fall when im done with my B20v-tec swap.

 

do a search for "idle"... you will find all you need.

 

Most people will tell you to change your IACV. Check that, and if that isnt it, its the plunger in your FITV) fast idle thermal valve). To fix that, take off the FITV, unscrew the 2 screws on the metal cover, and you will see a round "plunger" Shake the FITV and if you can hear something moving, you just found your problem. Take a screw driver and tighten the plunger all the way, re install, and enjoy your nice smooth idle.