i have a 93 F-350 with a 7.3 diesel engine with an automatic transmission whats strange is the way it goes in and out of gear at speeds of 25 and under also when i am pulling my travel trailer trying to hold a speed of 65 -70 it will do the same ...any ideas???

Time for a rebuild or Here (http://www.chevrolet.com/silverado/) ;)

Probably get a lot more answers by posting this question on www.thedieselstop.com .