I have a 1994 F-250 HD 4X4 with the 460 and E4OD. I got an error code 628(excessive torque converter slippage) after my trans starting kicking into gears. Check out my previous post describing it if you want

https://www.ford-trucks.com/forums/1427336-1994-f-250-transmission-shifts-hard.html

Anyway, I have ruled out a bad torque converter because I did a drive test where I drive 55-65 mph on a fleet surface and while holding the accelerator tap the brake and the rpm should go up then back down which it did. Apparently this means that the torque converter works. Which confuses me because the error code says it's failing. So my question is, what could possibly cause the code to appear? I get the code quite frequently, about a few times a month