What could be the reason?

When im coming to a stop or just to slow down, if im turning the wheel or even if i got the ac or heater on, my truck starts run like its got a big ass cam in it. some times it even dies.Let me add that it doesnt do it all the time. The dealership said it could be my throttle body maybe having some build up or something. it might just need a cleaning. Any ideas? what do you think it could be and how much are we talking about spending?

It also can be your torque convertor not releasing when you step on the brake. Check the switch and make sure your brake lights are lighting up every time you step on it. The brake switch doubles as a signal to unlock the convertor.

thats sound right to. makes alot of sense but yeah my lights do come on. is there an adjustment maybe?

If it's intermittent then maybe the switch doesn't work always. My 92/93 both had an adjustable switch down by the brake pedal pivot. I am not sure about the 99+ models if their switch is adjustable or not.

I TOOK MY THROTTLE BODY OFF AND IT WAS DIRTY. CLEANED IT AND GOT IT POLISHED. LOOKS NICE NOW AND IT ACTUALLY STOPPED IT FROM RUNNING LIKE THAT. SO FAR!

I had what sounds like the same problem on my yukon. I took it to the dealership to get a scaner hooked up to it. Man that was a mistake. They took my truck around back and came and told me that they could fix it for $70 dollars in about 5 min. I said ok and watched them spray a can of throttle body cleaner in the throttle body. Sure enough it fixed it. I would give the throttle body a good cleaning before you started buying parts.