I was driving to work this afternoon and my transmission (automatic) just quit accelerating and the rpms jumped up. I released the gas pedal and punched it again and it simply revved up the rpms. I shifted it into neutral and dropped it back into drive and hit the pedal again, this time it started to accelerate but wouldn’t shift out of whatever gear it was in. (I was doing about 50 mph when this all started). So I put it back in neutral and just stomped on the gas pedal 3 times. The exhaust dumped the most smoke my truck has ever dumped out before (it usually just puffs a little). When I put back into drive after this it drove fine the rest of the way to work but would still dump a lot of smoke if I stepped on the gas, at least for my truck. I have 105000 miles on my truck and the only thing aftermarket is a 4” turbo back exhaust with a muffler, no cat, and an sct tune with the canned performance tune downloaded currently. I haven’t changed all the fluids as I hoped to at 100000 miles due to no money right now. I haven’t done any towing with my truck since I bought it at around 92000 miles…. The owner before me did tow trailers for his oil company but nothing too heavy. Any opinions or ideas on what might have caused this? Should I ensure I get my trans fluid flushed and refilled asap (or just changed even)?