Recently the engine doesnt seem or sound to be getting enough power between 5-40 mph before kicking (with a significant jolt) into 2nd. I just put this new engine in, bought from chevy dealer, after blowing out the old one. had to drive it immediately from utah to canada after the work was done. ive checked all the fluids several times since the long drive and added more transmission fluid. the pickup on initial acceleration is lacking and obviously not working properly from the sound and feeling. any tips would be greatly appreciated

 

Maybe check the timing?

 

5 to 40 mph before it shifts to second sounds more like shift points are too high not lack of power - THM350 is a detent cable, THM400 is a TV cable both reset the same way - push the center metal pad in, slide inner shaft in then do wide open throttle and it will set shift points - picture of cable .....

 

Thought the first trans wirh TV cable was 700R4? Isn't the TH400 still detent cable?

 

Edit ... I stand corrected A standard TH400 uses a electric kick down switch on the throttle linkage that powers a electric detent solenoid on the valve body - The TH200R4 has a TV cable and is pressure control as with the TH700R4
If the electric switch on the throttle linkage is way out of adjustment it can be the same as a TV on the TH200R4 / 700R4 or a detent on a TH350 if way out of adjustment it will hold the shift points off and too high .....

 

well wonder if you put in a new fuel filter?? since stated a new motor ?