From a cold start, it goes through all gears and highway speeds just fine. After a period of time, it will just go out of gear and not catch, just revs up and will operate poorly or if stopped, not at all.

Turning off the car and restarting it makes it work again, but not for long. The first time it acted up, a filter change and a 2x3 fixed it for almost 6 months. Then it did it again, I changed the 3rd and 4th gear pressure switches and it ran, for a bit. Now its been months and I put in a magna inline filter and Hayden 677 transmission cooler in and that was the most complex mechanical work I have done to date.

So I take it highway driving and 30 miles away to sell it and whole it's cold, it performed beautifully. New owner take it, gets in inspected, and sometime later, the same issue occurs, stranding them. So, is there anything else to try? Do I scrap it? I don't understand why the transmission works cold and after a restart but then fails. I have also reset the engine by holding the gas down while in accessory mode on the ignition. After the last time I limped it home to a safe spot it finally spit codes, p0746 and and one about a solenoid out of expected range, I will need to check it again. Previously I took the control solenoid out and cleaned the screens. Thank you for any advice.

 

 

That code is for a pressure solenoid out of range or stuck off. My thoughts are the restart might unstick the stuck solenoid and allow it to work until it sticks again. Best bet is to take it to a mechanic who can diagnose the sensor issue. However, a rebuild of the trans may be in the future depending on how much the clutch packs have worn and torque converter over time. How many miles on the car?

 

Thicker fluid when ATF is cold, and thins out when hot. Worn clutch packs will show itself on thinned out hot ATF.