I have a 2003 F250 with a 5.4. Whenever I put it in reverse and hit the gas it stalls out. If I baby the pedal it doesn't stall. Now it is starting to stall when I come to a stop as well. Starts right back up each time. I was told it was most likely the lock up solenoid in the tranny. Interested in what others think. And if it is the lock up solenoid how difficult is it to replace? Thanks.

 

Vacuum leaks? Might have nothing to do with the transmission.

 

Put a code reader on it and see if you have any codes, This sounds more like a vacuum leak to me that it does any lockup solenoid.

 

Low transmission fluid can do this, too.

 

I agree. Check your trans fluid.