you are about 100 hp over the tranny's limit with the programming aready. Stock tranny will only hold about 90 hp (180 ft/lbs tq) over stock. Think about it, you increasing your hp by 200 and that equates to about 400 lb/ft of torque. That nearly doubles what you have stock. You have any codes? I bet you have a P1093. Start saving for a suncoast or ats tranny and torque coverter....you have to pay to play.
It is weird, normally when you limp the tranny, the only way that you can reset it is to shut the truck off and restart. You are slipping 5th gear pretty hard though if you are programmed to the 200 hp setting.