Transmission Problem?

Hello, my son has a 2006 Ford Fusion that he bought used. 6mths. after he bought it he started to have a problem w/the transmission. Runs fine on highway but when he would stop, then give it gas, it would not go and RPM’s would race up then clunk into gear and go. He had it replaced by the same people w/a new rebuilt one. It seemed fine for a bit and all of a sudden it started again. Also now with a faint ticking sound when taking off. Problem is he is now on a trip across the country from NE. to Oregon He has made it their safely but i have been meaning to write. Transmission or something else? Thanks, John (ps. auto transmission)

Classic symptoms of low fluid. Are there any leaks anywhere? What does the fluid level look like??

transman

He has checked the fluid. He had an oil change when he was on his trip and he did have all his fluids checked. When the car was at our house, i did not see anything on the driveway. Thanks, John