Superbeast

Hey everyone. New here. I’m an old school wrencher and I’m stumped on this one. My daughter has a 2004 Grand Cherokee. They were driving the other night, stopped at a light. Jeep was smoking and wouldn’t move. Had it towed home. I checked trans fluid. It’s clean and not burnt smelling. There was trans fluid spewed in the engine compartment. Cleaned it up, but can’t find a leak. Fluid level is good. Tried to drive it. Goes OK in reverse (about 20’) tried going forward and after about 15’ both rear wheels locked solid. Backed it back up put in neutral and pushed it forward. Scanned it and came up with 2 codes. PO734 and PO841. First is a 4th gear malfunction and second is trans pressure sensor. Tested the sensor as best I can (not a lot of room) and I have resistance readings. Not infinite, but I don’t know what they should be so I can’t tell for sure if the sensor is bad. Anyone ever have this issue? Ideas of what and how to diagnose? Don’t have $ to throw parts at it. Need to figure exactly what’s wrong to fix.