C3500 Transmission Shifting Problems

I am having problems ever since I changed my TPS sensor.  There are times that I start my Truck and place the transmission into gear and it shift hard into either D or R.  When I start driving the transmission instead of shifting around 10-15 mph for 1st to 2nd gear, it shifts around 20-25mph. All the other gears are shifting at the high end of each gear. It is like I am manually shifting my auto trans.  Usually when it shifts I cant feel the shift but can hear the difference in the pitch of the engine.....I have taken it into the chevy house and they told me that the connector at the TPS was bad and that it needed to fix that and it would solve my problem....guess what ,,,,,,it didnt fix it.....When the transmission starts shifting wrong, I can stop and turn the vehicle off and wait a few seconds and restart it and it will drive like a new one.....no problems. But all it takes is to turn my truck off and restart it and it sometimes goes back to shifting weird...please anyone help me with ideas..........I feel that it has something to do with the TPS sensor, because I didnt have the problem until I changed the sensor.......
 
Thanks Andy

Did you disconnect the battery when replacing the tps? If not disconnect it for about 10 min. If that dont help check to make sure the tps was installed correctly. The little levers on the throttle body have to be positioned to move the tps correctly. If all is well try a different tps. You might have bought a defective one.