I just replaced the engine in my 1990 accord. It has an automatic transmission in it and that part was working fine. The new motor is great but now when I take off it appears that the transmission is in high gear instead of downshifting to low. I can manually put it in low and take off and them put it in drive it shifts and runs great. It only happens when I take off after a complete stop. It worked great before the motor swap.

 

make sure the tranny throttle cable is adjusted properly