I always replace all fluids in any used car that I buy. Same with this one. I ran a Seafoam trans flush for 5 miles and then had the shop do a full flush and replace with fresh (Dextron III) AT fluid. Worked great ..for awhile.
Now I drive 2 miles to get on the Interstate and I can drive for 30 miles or for two miles at speeds over 70 mph with no problem. Until I stop.

After I come off the highway and make a stop it's like the transmission is in neutral - for all gears and reverse. I put it in Park. Turn OFF the engine. Count to five. Crank up the engine and it's like nothing happened...until I make another stop. Then it's the same thing.

At first I thought it may be a heat problem, but it "fixes" itself just by turning off the engine for 5 seconds. Which to me indicates it's electrical in nature.

I replaced the Transmission Control Module with a known good replacement, but after a short 2 mile drive it still acts like it's in neutral after I come to a stop.

Does this sound like Solenoid 1 and/or 2 are having problems?