I have a 2000 F350 with the 7.3 and 4r100 auto tranny.

I was recently towing up a steep grade and sprung a fairly sizable leak at the front of the transmission and had to use 2-3 bottles of stop leak to get it to stop draining fluid. Had no issues after the leak was fixed. Then about a week later the transmission started acting up when shifting from park to drive/reverse. But not from drive/reverse back to park. It takes much longer to shift into gear after pulling the shift lever to drive or reverse and boggs down the engine and sometimes even stalling it.

My question is if maybe the stop leak is too thick of fluid and makes this happen? Or if it is actually a mechanical issue. Maybe the stall converter took a dump? I have no doubt in my mind that it is in direct relation to one of my seals busting or the stop leak causing issues.

Just wondering if someone knows something that I don't before I go throwing parts at it or get a tranny flush. As they are both expensive.

Thanks,
Steve