'98 Starting problem when warm

I have a 98 Bonneville naturally aspirated. When cold it starts up and runs perfectly. Once I shut it off and leave it for a bit, it takes a lot of cranking to get it to started again. After it does restart it usually runs rough for a bit, and sometimes will stall when letting off the gas within a few minutes of restarting it. After I drive for a bit it runs perfect until I shut it off again.

Welcome to AF, check for raw fuel in the vacuum hose at the fp regulator on the fuel rail, post back, also when was the last time the throttle body was cleaned and are you loosing any coolant?

The throttle body has never been cleaned since i've owned it, but thats only been since July of 2011. I did have to add a bit of coolant, but again I don't know if it took a week or a year to loose that little bit since I didn't check when I bought the car.

It has 205,000 miles on it. Forgot to mention that, but thought i'd add just in case it was important.

Did you check the vac line like Max asked you to do?

Just removed the vacuum hose to the fuel pressure regulator. No fuel appears to be in the line, or leaking from the regulator. No noticeable change in the way the vehicle runs when removed either.

I think you need to check the actual fuel pressure ( 48-55 Psi )... I'd say either that Regulator is bad or the Pump is tired...

I did find out today I am loosing coolant. Can't see any smoke coming from the car though.

Well, if there are no external leaks, then the upper plenum is suspect......