E4OD banging gears

[Dieselfever]

I've got someone with a '95 (he just bought it), it has a Jasper trans in it that is supposed to be about 3 years old. When shifting from 1st to 2nd and 2nd to 3rd it will bang from one gear to the next. The more throttle that is given the harder it hits, downshifts feel good Also. Any ideas what could be causing it, the previous owner said it has done that since it was installed but the new owner wants it fixed where it will shift right

-Michael

 

[97powerstroke]

Mine did that when the torque converter was slipping and the computer would compensating by turning the line pressure up. I didn't feel like changing it so everything it would do it I would hook my scanner up clear the codes and it would be fine til I went up a hill and put a load on the lock-up clutch. I would try clearing it and see what happens since it was like that since it was installed if that's not it hook a pressure gauge up to see what the line pressure is.