my truck has been "missing" and sounds like it is about to die while idling. I have had it dealer last week for an oil change, belt replacement, and spark plug wire replacement (1). What is going on? Is it the fuel filter?

 

Idle air control sounds like a winner to me.

 

Turns out it was a spark plug. Need to replace all plugs and wires. Dealership want $457! Wow! Going to do it myself.

 

While you are at it I would change out the distributor cap as well.

 

Don't have a distributor cap on 06, but yeah you can do wires and plugs for about $130 yourself

 

Yup do it yourself. Make sure to use either AC delco iridium plugs or NGK tr55s

 

Your truck will run a lot better with new plugs & wires. As someone else said, there is no distributor cap on the 5.3L like there is on the old 5.7. They have "coil on plug" or whatever it is called. Ah, technology!

P.S. I had new plugs & wires done by a GMC dealership just before 100,000 miles and it made a huge difference in how the truck runs.....but it still eats too much gas.