How much is my 2006 Mercury Mountaineer worth?

2006 Mercury Mountaineer Idle Fluctuation?

• i have a 2006 Mercury Mountaineer with a v6. When coming up to a stop the throttle goes up and down from like 500-1200rpms. Then at the stop it runs at 500rpm almost as if it were to stall out but it never does. There is no Check Engine Light. I just visually looked under the hood and check the air filter and everything appears fine meaning nothing unplugged or anything. I was going to unplug the IAC to see if it stops the idling up and down and doesnt get worse. I'm thinking if unplugging the IAC and it doesnt get worse and fixes the idling up and down that I have a defective one. What else should I check and how to check them. Thanks in advance for the advise.

• Answer:

  Hi If this only happens with a hot engine then you could have a sluggish O2 (lambda) sensor, but this can only be diagnosed via a diagnostic scan or by replacing the sensor. You may have an intake air leak. Check all intake pipes & hoses for condition & security. You can spray starting spray or similar around the intake pipes & seams with the engine running. Any change in the engine sound would denote a leak. You could also have a dirty idle control valve, or IAC as you call it. Whip it off & give it a clean. Very best regards Geordie