Hello all I need help... ok first off if there is something wrong with main radiator hose that runs into the thermastat houseing will that make the tranny slip some like not want to go into a gear or slip out of it making the motor rev... this jsut started doing it a few days ago both days it's been raining so I'm not sure whats wrong but I'll get going at about 25mph where you would think it would shift it tacks out and seems like it's slipping in and out of gear, I let it sit all night and took it out this morning and it didn't seem to slip I'm at a lost lol plz let me know if you guys have anything to help thanks a bunch

 

btw it's a 93' f-150 stright 6 4.9L auto

 

Just an update I took it out again, it didn't start slipping till I got off the highway, I went to a buddies house and he said to flush the tranny and change the tranny filter what do you guys think? plz anyhelp is needed at this point ty