OK, I've obviously got a serious problem. My idle is all over the place. After the truck has warmed up, and I've been driving, when I hit the clutch to slow down, the idle drops sometimes to normal (7500, I believe), sometimes only to about 1250, and other times, drops below 500 and the oil light starts to flicker - and three times now it has completely died. If I catch it in time (below 500), and give it gas, it keeps going like normal.

At first, I thought maybe it was the Fuel Sending Unit going bad - but I just had that replaced under the recall, and the truck is doing the same thing.

Any ideas? Would the fuel pump be doing this if it was going bad? The first occurance was about three weeks ago - then it was fine for a week, then did it again and now it's sporadic. (I've had the truck at the dealer while I was in Ohio, so I wasn't driving all the time with this happening).

If it is the fuel pump, is this covered under the extended warranty?

Side note - any chance I could get the e-brake cables covered under the extended warranty? I can't see how those would really be considered a "normal wear" item - as opposed to the actual brake shoe.

Much thanks to anyone who can pinpoint what may be wrong.

Sounds like a possible IAC valve going out. I'd want to check the Idle Air Control (IAC) valve with Consult II to insure that it either responds correctly, or fails.

Also, could be a Mass Air Flow (MAF) sensor going out as well.

But, this is stricly conjecture, as I'm not there to see the little things (massive sucking sounds when this happens? erant spark noise? A/C compressor on due to defrost being on? Battery condition? Alternator condition? MIL light on? etc...).

There isn't any odd sounds that I can tell. Though I hadn't thought of the A/C causing anything - I couldn't say whether it was doing it only while it was on or not.

The alternator is less than a year old (replaced under warranty), battery is less than a year old (Red Top).

No problems with start up, so I'm assuming it wouldn't have anything to do with the alternator or battery. No warning lights have come on at all (except when the idle is dipping to near zero).

I would definitly look at the IAC valve. You can normally take it out and clean the pintle with carb cleaner and the inside of the throttle body that the IAC vavlve goes into (make sure it is O2 safe). Sometimes carbon and gunk will build up and it can't move freely to adjust to proper RPM. I had a similar problem on an older GMC Jimmy. Cleaned it and that was that. The IAC valve adjusts the amount of air going into the motor when the throttle is closed, like when you are stopped. When too much gets in the RPM's are high. When too little air gets in, the engine dies. This is why when you blip the throttle it keeps running. You Can also have somebody with a scanner check the voltage at the IAC valve and the MAF as Cyclemut suggested and compare it to a known good value to determine if the sensors are working properly. I'd start with cleaning the IAC valve first, then going from there.

But to get to the IAC valve on the X, you have to take the upper plenum off. It's in the back, mounted underneath the upper plenum (common chamber).

That sucks. But what is he supposed to do? It sounds like he is out of warranty and doesn't want to spend a lot of money at the dealership. Never mind, I just saw where it looks like he has an extended warranty. In that case Mobycat, use it!

what is the plenum?

Intake manifold.

Just calling it an intake manifold would be too easy for manufacturers. So, they call them plenums. Especially if it has multiple pieces (i.e. Upper plenum, lower plenum).

Some manufacturers call them common chambers, but we don't say the 'H' word here.