When I am hard on it, it dosn't wanna shift out of first. I can run it all the way up to 6k RPM, and it wont shift, but if I let off, and let the RPM's drop to say 3k RPM, then it will shift. The tranny was replaced under warrenty just a few months ago, and I am now no longer under warrenty. Any idea what it could be.

 

My dads truck does it when its hot out, it gets real sticky on the shifts like you describe and blocks out 4th gear (its a 4 speed). Does this happen on short drives or mainly long ones?

 

Pretty much everything that is a hard drive. If I drive "normal" it shifts fine, but getting on the highway or anything, forget it. I will try and snag some video tommrow.