Check your ignition timing at cranking RPM and see what it is scope
If it is 18 BTDC or more that may be your issue on the motor kicking back on the starter when warm or hot scope
Been there, done that realcrazy
Try having the initial, idle timing set at 17 degrees or less and the total at 34 to 36 degrees BTDC and see how that works for you up

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)