High idle, stalls on cold starts.

Ok ill give you a quick rundown on what ive done sofar to try and fix this problem.

First off, it started to idle high, around 2000 then in a second or 2 it'd drop to 1500.
I cleaned the throttle plate, removed the IAC and cleaned the tip and surrounding areas with throttlebody cleaner. I was told it could also be the MAT sensor, so i took it out and tested it with a multimeter but was unsucessful at determining if it was faulty or not. Being as it was cheap enough, i just bought a new mat sensor. One thing to note (if its of any importance) the Mat sensor was the exact thread size as the stock one but did not thread in all the way, only 2-4mm of the tip are coming through the other side into the air filter housing:

This is the old one, the new one doesn't go even this far into the houseing:


After all this, i started it up and it idles at 1500rpm still, im gunna know for sure tomorrow weather the stalling problem is fixed, it only really happens when i get up for work at 3am and its cold out. Besides these things ive done, i dont know what else to try and rid myself of the high idle and stalling problems.

I need some suggestions here.  Thanks

nvm it was the sensor, all is well now. 

They can't hurt...
But I doubt it'll solve your issue.

You really need a scan tool attached so you can read all your paramaters when it's cold.
Have you ever had the injectors (including cold start) properly serviced?

You really need to read your MAP sensor value in action too.

O2 sensor won't even read for 60 seconds after you start up, so ignore that unless it's really old anyhow (use a Delco one to replace it).

You need to get a sweep on your TPS.

You also need to get a reading off the ECM's temp sensor.


That's all that pops into my head!

Tough call - really depends how much you can do yourself (sounds like you know which end of a wrench is up though).

The injector service depends how long you're willing to be without the car.  You can buy a whole new $et of them and switch them out.  That's the shortest route (oh, you can't buy a new coldstart anymore, so you will have to buy/borrow another and have it cleaned).

You can have your current set cleaned, but you'll be down for a week while they're being done.

If you show up to a meeting and it's not raining (hahahahahaha!) and give some warning, I can bring some toys along and check your TPS and MAP.

If you just bought it, then I'd blindly replace the O2 - just use a 7/8" combo wrench...  and pray the threads don't pull out.

I assume you've already replaced the air and fuel filters and PCV?