I got a 2000 Silverado 1500 5.3 4x4

Just had the transmission rebuilt by a reputable shop near me. When i got the truck back it was shifting kinda hard from 1st to 2nd. I put 500 miles on it then decided to see how it would do flooring it from a stop...

Took off awesome but when it went to shift into 2nd it redlined and didn't shift until i took my foot off the gas pedal.

Figured it was the throttle position sensor, nope. That fixed the hard shift from 1st-2nd but it still redlines and refuses to shift into 2nd at wide open throttle.

Any ideas?

 

Take it back to the techs who did the work. They scuffled something up

 

next time take it back before you put 500 miles on it and dont go flooring it when there's something wrong with it. think about it