I am having trouble with a very low idle. During cold start it will idle between 1300-1600 and after it warms up it will drop down to 300-500 rpms. When at stop lights it will search between 200-300rpms; and other sometimes will idle fine then drop suddenly. It will almost stall with AC on at idle, but does fine when I'm in motion.
I have replaced the FITV, cleaned the IACV and throttle body and checked MAP. Still having this problem. Today while on the highway I noticed that It will vaguely jerk when accelerating, and in the city it will jerk as if I were a beginner in manual transmission. It's really starting to frustrate me, and before I take it to a stealership was hoping to get some info on possible problems I could fix myself.
Thanks in advance.

 

Does the check engine light turn on for 2 seconds when you first turn the key to the II position? This is normal to make sure the bulb works.

Does the check engine light turn on while driving? Does the D4 light start flashing, if you have an automatic transmission?

Are the maintenance items up to date, like distributor cap, rotor, and spark plugs?

 

Yes, the CEL comes on for a few seconds if I put the keys in the 2 position. Other than that the CEL doesn't come on. I don't have a diagnostic connector, but have done the paper clip trick with the blue connector under the glove; no Morse code signals. I have a manual transmission. No clue what a D4 light is... and the Dis cap, rotor, belts plugs wirse were done a few months ago..

 

Your MT car doesn't have a transmission computer, so ignore the D4 part.

You may have to clean the throttle bore and both sides of the throttle plate. Also clean the screen on the IACV with some TB cleaner.

Reset ECU by pulling 7.5 amp backup/radio fuse in the engine bay fuse box for a minute. Start the car and allow it to warm to operating temperature.

 

I've cleaned all of the throttle body, IACV and replaced the FITV a few days ago. Same problem. Thinking I may try and replace the fuel filter and hope its not the fuel pump..

 

Let it cool off completely & reset the ECU.
Start it without touching the gas pedal.
Let it warm up without touching the gas pedal.
(this forces it to re-learn the idle behavior)

 

I have done all the steps for the IACV, FITV and Throttle body cleaning etc. awhile back. It is still at a very low idle, I have also tried to set it by turning the idle screw; marked original setting and turned it back, because it didn't help either. Is there any other cause besides the throttle body and its components? My PCV is good, as well as the dis cap wires plugs alternator. I replaced the fuel filter this weekend and still having issues....

 

Would bad engine mounts cause this?

 

Shouldn't be the engine mounts.

Looking back through the thread, I don't know if you set the base idle...

Warm up the engine & turn OFF EVERYTHING (lights, blowers, stereo...)
Unplug the IACV. (it'll want to stall so nurse it with the throttle)
Adjust the idle screw for 550 rpm.
Turn it off, let it cool down, plug in the IACV.
Then do the steps I said in post #6 to force it to re-learn.

(Or did you already do all of that?)

 

Yeah, I have. Cleaned the throttle body and all of its components and adjusted the idle screw, but set it back to normal setting because it didn't do anything. That's why I'm looking for other causes. Thanks.