Extremely weird...Transmission shifts itself in Neutral..??

[PowerstrokeDiesel]

I was pulling into a restaurant last night and as I hit the parking lot the truck seemed like it was in neutral. (not sure if it was in neutral didn't try any elimination procedures simply just left it to have a good time, but i do know that it just revved and that's it..had all engine power) I pulled into a parking spot ate dinner and when I come out hoping all would be ok, my alarm wouldnt unlock the doors. I go home grab my stock remote truck unlocks..alarm goes off...I proceed to hit the unlock button..nothing. I re-sync the remote/alarm remote it unlocks. I start the truck no problem and drive away..no problems. No over heating problems either which is another issue I've had with the tranny.

2003 F-350 FX4 7.3 original tranny cooler, 4inch exhaust, 35 in tires, 4r100 tranny, 142,000 miles on truck and tranny

Truck seems to be possessed right now lol acting on its own. Truck runs good for now...but plan on taking it in to have tranny worked on and hoping to solve the issue. But any insight would be greatly appreciated.

[PowerstrokeDiesel]

Did some process of elimination today and drove great shifted good. Buuttt, when I parked it I just sat there and went threw the gears..N-revs up but comes back to original idol rpm
D-just stays the same for the most part minor movement
R-Idols down like its got a load and in some cases it died. I repeated this process several times