transmission question
 

I have a 2001 chevy 1500 Z71 4x4 with some transmission issues. It wont go into tow haul mode. At about 1500 to 1700 rpm it acts like it cant decide weather it wants to be in over drive or third gear. I have heard maybe a vechicle speed sensor. need to make it right dont want to have to replace the transmission. hope to get some help thanks alot.

Im not really the guy to help with and automatic tranny but I have read on here about problems that are simillar so just to get the ball rolling a little bit maybe check out your crankshaft position sensor. my girl friends went out and it did the whole between over drive and 3rd thing and when it did that it would almost feel like it wasnt getting gas or something. if nothing else it should be an alright place to start