I'm thinking you've got a fuel injector leaking. After you shut if off, the
leaking injector drips fuel into the intake manifold and causes a very rich
mixture on hot restart. When you open the throttle butterfly all the way,
(by holding the accelerator all the way to the floor), you're allowing
enough air to mix with the excess fuel to make a combustible mixture. When
it's cold, it needs extra fuel to start, which explains that symptom. Pull
the fuel rail with the injectors on it, and just turn the key to on, not
start, to pressurized the fuel rail and check for one of the injectors
weeping fuel. Just my .02 and hope it helps. Had this problem on a '92
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