You did clear all codes when the new tranny went in? Usually if the ecm is bad, it wnt idle well either. May be the egr is sticking, or opening the wrong time, there is also a known fuel pump problem on these trucks, the cure was a new style pump. There also was a problem in the plastict intakes, the gasket between the two halfs disintegrates, and you get vacuum leaks that show up as codes p0171 and p0174. Spray some throttle body cleaner on the intake at the corners and the seams, if the idle changes, you have a leak.
Wednesday, September 24th, 2008 AT 3:03 PM