anuvanoob

One of my vehicles has an aftermarket transmitter and receiver set (cheapo bought from Amazon, I forget the make and model). The transmitter has a low, medium & high speed switch which worked well. I just swapped out the motor and ESC (again, cheapo from Amazon) and during testing (putting it on a lift) the wheels continuously spins only when in the low setting. When switching to medium or high speed via the switch on the transmitter, the wheels spin for about 1 second then stops. Oddly, when switched to high and turning the throttle trim far to the left, the wheels start to spin continuously, automatically, but then I give the trigger full throttle I get high/full speed continuously (indicated by the ballooning of the tires) - the wheels no longer stop after 1 second. Obviously I can't operate the vehicle with trim set that far left as it will spin automatically without throttle. Any ideas why the car runs for 1 second then stops when in the medium or high speed setting? Any ideas how to fix?