Bad@$$ Beth the XJ

New here I have a 98 Cherokee Sport 4.0, 6 cyl automatic with 105K miles. The day I got it back from having the heater core replaced (in early Sept), it started going into limp mode after a short stop - aka, I drive it just fine to the grocery store, stop, shop, and when I come back out to resume driving, it will not drive in D. I am able to manually shift from 1-2, to 3, to D, but will not work in just D. The solenoids have been replaced, and, just yesterday, the TCM - no resolution of the issue. Current shop says the transmission is showing -40 degrees so they think it may be the internal transmission temp sensor, or that I need a new main computer. We have explored other options (fuel pump, torque converter, etc) but doesn't seem like those issues would cause the vehicle to not drive properly ONLY in D, not the other gears. It also sounds a bit rough just idling in Park. There is no engine light on. I'm at the end of my rope here, with it going to 3 repair shops and 2 transmission specialist shops ("we can't do anything if the engine light isn't on") in the last 2 months. It's in pristine condition with low miles so I would hate to have to get rid of it. Any insights would be greatly appreciated!!!