sounds like tv linkage problem 03 be the last year with that if im right, check fluid level in neutral if that dont fix it check the band adjustment and gov. pressure

 

Check your negative battery post as well. Make sure they are tight. Seems odd, but it may help.

 

I am having the same problem. Does the 07 5.9 need band adjustment too? If so is there a link anywhere for that year with spec's. I found older year spec's.

 

what is the procedure for adjusting the tv adjustment, the bands have been checked, the fluid is good, the battery connections have been checked and it has new selenoids in the trans.

 

look at the driver side next to the shifter the tv lever shaft is inside the gear shift shaft, there isnt much adjustment but there should be a spring on the front side... theres a sleeve on the cable have someone hit the pedal and make sure it isnt binding up and check the other end of the linkage at your tps

 

Likely the gov circuit is flooding with line pressure and stalling the shifts. Did you use the GM upgrade governor solenoid? Almost a must on some builds.

Backing down the WOT TV pressure might also help some but ti may soften your light throttle shifts too much. Just have to try it and see.

 

I did use the gm selenoid when i changed them out as i had read this might help as it turns out adjusting the tv cable does made a big difference and it doesnt take very much adjustment to make a difference so any one else doing this do it a little at a time thanks for the help.