95 Cougar V8 refuses to shift.

Hey all, so I've got a bit of a dilemma. I have a 1995 Mercury Cougar that just refuses to shift. First off, it's automatic, just to be sure we're all on the same page. When I put it any gear, it's almost as though it's in neutral until I put my foot in it and get it up to about 3000 to 3500 rpm. And even then, it stays in first gear. Additionally, it usually has fairly high rpms and kicks when shifting from second to third sometimes. No other problems that I can tell. Plenty of fluid, doesn't smell burnt. I was thinking it might be the ECU, but that doesn't seem likely since the shifting problems are the only issue present. Oh, unsure if this is related, but when I start it up at the beginning of the day, the low coolant light comes on. I have plenty of coolant in there, and after it runs for a bit, the light shuts off on it's own.

I believe the transmission cooler lines are attached to the drivers side of the radiator for that car. Those types have been known to crack internally and let coolant get into the trans fluid. The coolant will then swell and ruin the clutch packs for the transmission. A new radiator and trans rebuild or replace is then needed to fix. Best take it in to get tested.

Yeah, the testing was what I planned on, I just hope I can find a good shop to take it to that won't try to charge me OTA for it.