Replace my transmission & torque converter in my 04 with one that I bought from pull your part yard (another 04 TL transmission). Installed and replaced with new fluid. She ran fine, shifted strong and firm. After about an hour it would down shift correctly. Changed fluid a couple more times doing the 3x3 method with Honda trans fluid. Now the car will run fine for about 7 miles and then acts like its low on pressure. If I stop and try to go it's like the torque converter won’t engage. I can turn off the car let it sit for about 30 secs and turn it back on and move for a few more miles before it has issues.

Odd part is it runs fine and shift normal but seems like once it reaches a certain temperature it won’t engage.

I still have my original torque converter and thought of swapping in to see if that fixes the issue.

Any insight is greatly appreciated

 

If it shifts fine, when in a lower gear other than D, then you have a torque converter or torque converter clutch issue.

The torque converter partial lockup happens as soon as you hit second gear, but it does not do so when you drive in a lower gear.

 

Did you change the pressure switches?

 

yes switches were changed. There is no shutter between gears.