Good afternoon all. New member here. Looking for some help from people who deal with these every day. First off first 6L80. Tuned on HPtuners. I'll try and give as much back story as I can. Bought out of Texas and runs and drives great....under normal conditions. Shifts perfect until you reach half throttle. 1-2 and 2-3 1/2 to 3/4 throttle sends itself straight to the rev limiter. Stopps pulling about 4500rpms. Let off it completes shift and goes about its business. I have went back to a complete stock tune, had tuners play with it, no transmission codes, etc. Fluid levels seem to be correct, running Dextron VI. We are all just baffled. I am attaching the current tune for reference. I am about to the point to command the shift at 20mph and 3000rmp's just to see if it will stop.
Any help you all could provide would be much appreciated.