need help

[conman3300]

ok well i need help bad because i have no idea how to fix it.

so problem starts after i take my truck to ford and get it back.It shuts off if i put it in reverse and kinda shutters if it doesn't.so take it back and they say there's no problem so i get it back and same problem so take it back again they say its my alarm so got that fixed.now still same thing still shutting off.So it finally quits for a bit so i put my chip back in and iv noticed when im in the 80 setting and have to stop fast the truck just shuts off and the reverse problem came back.

So now i have no idea what it could be and don't no where to start.

any advice would be great im scared to drive it because of it turning off so any ideas ill try.

thanks

[SCUFFY828]

sounds like torque converter locking up when it isnt supposed to