My 93 5.0

I towed a trailer 100 miles. Ran great.. in morning it started fine and I went 2 miles. Reverse would cause a stall. It would work if I gave a little throttle. Next, about 10 minutes later it feels like I'm slipping and in neutral. It does grab and jerk and over 40mph it's ok. If I hold brake in Drive, it wants to stall only after about 30 seconds. Idles fine...

Tran oil is fairly newer and still red. Reads high??? And a slight foam on it. Btw I'm in the deep woods.