I have a 97 buick lesabre 3.8 v6 giving me fits. Engine won't start after driven and engine hot. I can release pressure from the fuel pressure regulator and it will restart and be ok until I shut it off and try to restart it. Same procedure and it will start up. Engine starts ok when it is cold. I replaced the fuel Pressure regulator and still have same problem. Any ideas?

update: engine will also occasionally stall at stop lights, or when at idle in gear with brake on,(like at the top of interstate exit ramp. I have also replaced the throttle position sensor and the maf sensor.

see if you have spark when it wont start, its more likely the crank position sensor or icm

Well it does have fire, just won't restart til it cools off or I relieve fuel pressure.

you put a pressure gauge on it so you can see what its doing when it quits?

not yet. have to get a pressure guage.

Just checked fuel pressure at Schrader valve on pressure regulator. With engine off fuel pressure shows less than 10 psi. However engine starts and runs ok on interstate. Engine has not died yet to check pressure then. has not died

Checked f/p reg vac line for fuel?

Huh? where? checked at Schrader valve on top of fuel pressure regulator

Watch that, skip ahead to 1:50 mark for the relevant part.
The Schrader valve is not on top of the fuel pressure regulator, it is under it.