so i have searched and searched but no luck on this one. on cold starts i start the car in 1st to prevent the 3000 rpm warm up and it idles around 1200rpm or so. the rpms will slowly drop until the car is warmed up but in the process of doing so from 1200 rpm to about 1000 rpm the engine sputters/shakes. once it gets to 900rpm the idle will bounce to 1100rpm for a couple minutes. so about 5 to 7 minutes have gone by now and the idle becomes normal around 800 rpm. when warmed up the idle is great and i dont have any problems what so ever. i am running the stock ecu with intake, dp, catback, and cooling mods. please take a stab at this on. tps is within specs.

 

Start by following factory recommended diagnostic procedures. After the engine is completely warm, do the idle set procedure in the service manual. 800rpm is a little too high for a no load idle, spec is between 700-750. Make sure A/C, lights, blower, defrost etc are all off.



Then see if that affects your next cold start. If that doesn't help, you may also want to remove and clean the ISC valve.

 

checked the idle (warm) on the way to work today when warm and it is around 700. i will try cleaning my isc valve. i think in the fsm it is talking about the idle when it is warm. i think my isc may be the issue. every now and then i get a weird idle after a good pull for a moment which has got me thinking about my isc sticking. thanks for the help.

 

after you clean it, set the idle using that procedure ^. What that procedure does is set the baseline amount of air that bypasses the throttle plates regardless of ISC valve duty cycle. That affects the closed loop idle logic. When you jumper the diagnostic connector you are temporarily setting the ISC valve to a fixed duty:



you need to make sure all the air bypass passages are clean: