<div class='quotetop'>QUOTE(RedHeartbeat &#064; Mar 29 2006, 11&#58;05 PM) [snapback]48708[/snapback]</div>
The program in the PCM controls upshifts taking into consideration the throttle position percentage. If you consistantly accelerate at about a 30% or greater TPS load it should upshift religiously. If your internal shift solenoids do not have the built in filters you should replace them just for safe measures. I had to do that on my trans when I rebuilt it. You could also have defective downshift solenoids.

Does your trans shift 1-2 fine but when you expect 2-3 shift it free revs like you stuck it in neutral? Do you have a stall converter greater that 3200 rpm? If so, you&#39;ll have to disable a couple PCM codes to keep this free-wheeling from happening. I drove mine like that long enough I eventually destroyed the transmission. Does your transmission have a vacuum operated fluid pressure device on it and if so, does it have a good vacuum source to it?
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Thanks for the info. The truck shifts fine in normal driving conditions 1, 2, 3, OD, R, P, N. It just doesn&#39;t want to downshift when at part throttle and then you mash it. The stall is somewhere between 21 - 2300rpm. Not sure about the downshift solenoids, but this could be part of it I guess. I don&#39;t know if the tranny has a vacuum operated fluid pressure device. How can I check/confirm?

Thanks for the help man&#33;