I have replaced all vacuum lines, replaced the following: EGR Valve, TPS, IAC, o2 sensor, rebuilt throttle the body, replaced the water pump, radiator hoses, temp sender, checked vacuum booster and flushed the cooling system. Truck is not posting any engine codes. This truck will idle about 2000 rpm then as low as 200 and fluctuates back and forth. It has stalled on occasion. Although sometime it will idle normally but that is rare. I have also replaced the exhaust manifold on the passenger side as it was cracked. Last year during winter season, I had trouble with engine at operating temperature but no heat. I had flushed the system, replaced the water pump and that resolved the problem. There is no oil in the cooling system.
Wednesday, December 28th, 2011 AT 8:09 PM