So I have my 04’ Trailblazer Ls and I’ve had it for a couple months now with no issues on the engine or any ongoing codes besides a Evap leak, whenever it shifts from first to second it feels rough as if you don’t rev match in a manual. And when I slow down it drops below 1K RPM and feels like it might stall..
Any ideas on what could be?

 

Be advised - if the vehicle is equipped with the 4.2L I6 engine, the throttle position sensor is integral to the throttle body. There is no replacing just the throttle position sensor.

To the original poster - how many miles are on your TrailBlazer? Are you sure the transmission fluid is filled to the appropriate level? Do not consider a transmission flush!!! Only do a pan drop and filter change is you desire to change the transmission fluid.