1990 Thunderbird Super Coupe hot start issue

My wife's '90 SC does everything right except start and idle when hot.

It starts great when cold, runs like a champ all day, lots of power. The problem we are having is that when she stops for groceries on her way home after driving 20 miles, when she comes out 10 minutes later the car will start but will idle low and rough and sometimes will stall. When the motor is hot is the only time when this issue occurs. I've replaced the IAC and the ICM on the car and can find no vacuum leaks. Someone suggested faulty fuel pump but that doesn't make sense because, again, it starts and runs fabulously all other times. Anyone have a clue?

I had a 93 Taurus that had a similar problem, it would start great when cold then crummy when it was warm. Was a bad fuel pressure regulator.