I am concerend that you may have both a weak tranny and the engine problem, because even if the engine is running wild the tranny should hold it down, because on the road there is resistance to the engine reving. Lets think about this for a second, if you floor your truck while running down the road at say around 60 MPH what does the truck do normally, it most likely will shift out of TCC lockup, and maybe out of OD, but the engine should never run wildly to redline unless the tranny is slipping or something else in the driveline is faulty.
Did you have any codes with it, because a few people have had the APP sensor problem, as mentioned by CharlieP. they get dirty and are no longer a linear curve, rather a realy unreliable landslide, that could cause the uncommanded reving, but should not be the cause of the tranny slipping alowing the engine to redline.
This is just my thinking out loud, and by all means if they are willing to replace the IP under warranty than get it, but don't be suprised if that doesn't fix it, but at least you will have the new IP
Edited by: CAT 3406