2000 chevy blazer transmission shift issues

2000 chevy blazer transmission issues2000 chevy blazer,transmission shifting from 1 st gear to 4 th gear. Changed trans and second trans doing the same thing. Changed tps sensor also. Truck seems to do ok when it shifts to high gear, but rpm gauge goes very high before it shifts. Anyone experienced this problem please share your diagnosis, it would be greatly appreciated.thank you hadley3119

2000 chevy blazer transmission issues2000 chevy blazer,transmission shifting from 1 st gear to 4 th gear. Changed trans and second trans doing the same thing. Changed tps sensor also. Truck seems to do ok when it shifts to high gear, but rpm gauge goes very high before it shifts. Anyone experienced this problem please share your diagnosis, it would be greatly appreciated.thank you hadley3119

You either have another bad transmission or transmission computer or bad wiring.
You need to get it on a transmission capable scanner and get codes and read out transmission data.
Post back any codes.

yes, it amazing how proper diagnosis, if followed can save a lot of money....

Many times, have seen transmissions changed, and the problem was a broken wire in the harness somewhere, that controlled a shift solenoid.....

Was this a garage that diagnosed this and said you needed a tranny?