First time down the track

IIRC, flash stall and stall are two different values. In gear brake hard enough car doesnt move, feed it throttle until the rpm’s stop increasing is the stall rpm. Flash is just slightly higher. You hammer the throttle quickly until the engine stops gaining rpm. The rpm’s flash higher the settle down to steady stall. The highest momentary rpm is the flash. The steady rpm is stall. Spend the shortest amount of time possible during the test and the car may push through the brakes. You would be surprised how much heat this will generate. I don’t think this is converter issue