club car
 

Electric 48 v when I start off if I press pedal softly cart go fine after moving if I press hard on pedal cart stalls and I have to let off on pedal to lower speed and cart runs good again

If your cart is newer than 2002 it could be your Mcor ( The Potentiometer that acts as the accelerator) and that should show up as a fault on the plug in programer device for Club Cars.
Older carts, you have to start a test procedure the starts at 1-V glide 2- solenoid 3-controller Sorry, there is no simple answer without testing with test equipment.