I just finished working on a 1/2 hr hot restart problem on my 1989 Riviera. Acted like it was flooded and once restarted would stumble at idle. First thought was a leaking fuel injector. Was about to pull all injectors to see if there was one leaking but pulled the vaccum hose on the fuel pressure regulator first. It turned out to be faulty Fuel Pressure Regulator diaphram leaking. I found it by just pulling off the vaccum hose that is attached to it and saw fuel dribbling out of it. Start engine and watch it for a minute or so it maybe intermittent. Good Luck JohnR