Transmission bad?

[FX4 F2-Fifty]

To start out the truck drives fine when your just driving it "normal". But under WOT it will not shift right MOST of the time. I had noticed when i was on the beach that when it would spin it wouldnt shift it would just lay into the rev limiter. Well today i pulled out of a parking lot and a car came flying up on me so i put her to the floor....black smoke........black smoke......some more black smoke.... then the turbo spooled..... it spun and then hit the rev limiter and stayed there so i let off. Well when i let off it coasted for about 100ft then "CHIRP CHIRP" the rear tires locked up. Sounded like it hit 2nd going about 40mph but quickly returned to normal. Trans temp was good. Any ideas?

[CT Performance, Inc.]

How long has it done this?

[FX4 F2-Fifty]

First noticed it about 3 months ago when i put it to the floor from a dead stop and it hit the rev limiter. Never really thought anything of it as i rarely floor it from a dead stop. I changed it to stock. Then back to the street tune just now and the rev limiter was set on 4150? so i set it to 4350 and im going to go see what happens...