I have a 2000 Expedition that has lately been trying to stall when stopping. When you apply the brake to come to a stop the rpm's will start to fluxuate and at time the engine will stall. I was told it might be a bad IAT sensor and to check this sensor as well as the tube it goes in to.

My truck has the 4.6L engine, where would this sensor be located?

 

You are looking for the IAC (Idle Air Control) valve, not the IAT (Intake Air Temperature). Sadly, I don't recall where it is on a 4.6, but it's silver, cylindrical, has two wires going to it, connects to the intake with two bolts and has a 3/4" hose going to it from the air inlet tube after the MAF.

 

Christmas night last year, we got into the Expedition to go home and it started very roughly and just as soon as I took my foot off of the gas pedal in order to press the brake and put it into gear it stalled. I tried to start the motor 5 times and same results. I got a new Borg Warner IAC valve at O'Reilly Auto Parts for $73.43 and 30 minutes later (the next day) I had it fixed. I probably saved $150. If this sounds like your problem...

1. Disconnect negative terminal from battery(5/16"). Two reasons, safety, and the engine computer has to be provoked into calibrating the new IAC to work with your engine. Disconnecting/reconnecting the battery will accomplish this.

2. Unbolt the three bolts (10mm, I think) that secure the plastic "4.6" cover to the top of the engine.

3. Find the little SOB. It's on the driver's side, looks as described.

4. Unplug the two-wire harness from it.

5. Unbolt the old IAC (two bolts, 8mm) and remove the IAC and the old black mounting gasket.

6. Bolt the new IAC in its place. Don't forget the new gasket!

7. Plug the wiring harness you unplugged in step 4 onto the new IAC.

8. Put 4.6 cover back on.

9. Reconnect negative terminal to battery.

10. Start engine and let idle for fifteen minutes (Don't touch the accelerator!) to allow the engine management system to learn how much voltage the new IAC needs to perform it's job.

I borrowed this info from another post. I think it was on another forum too.

 

I took mine off and cleaned it last year, about 30K miles ago. Still working fine and it didn't cost any $$$.

 

there are directions for cleaning this on "idle air control valve-cleaning-Blurt it" from what they say you must be very careful not to get any liquid on the electrical side, but i think that you can also test it per instructions in the haynes manual, you need a digital meter. good luck!