2003 Mustang

No start condition when hot, does point to an overly rich condition, in which depressing the gas pedal while cranking puts the ecu in "flood clear" mode which doesn't fire the injectors while cranking.

Shawless said:

I drive the car everyday and for longer periods.........I'm just baffled because it didn't hesitate and it didn't give me any indication anything was wrong

Click to expand...

So, does the car start if you depress the gas pedal to the floor during the times it won't restart?

If it does restart then, it points to an overly rich condition which can be caused by a failing sensor (ECT or ACT)

Other questions. Given the car is 19 years old, does the check engine light bulb work? I beleive 2003's were still using incandescent bulbs for the warning lights in the bottom of the cluster. Does the CEL come on if you turn the key to ON, but do not start the car?

Is the CEL illuminated at all? If so, are you able to hook an OBD2 scanner up and pull the codes?

@Nightfire @manicmechanic007
Just for the sake of discussion, a flooded engine condition can happen with a FI engine but not like a carb'd engine, of course with a carb every time you press the go peddle fuel is squirted until the float bowl is emptied, but we all know this, so what happens when you press the go peddle on the EFI engine key off, not running? Well nothing, even when the key is turned on, there may be a quick little spritz of fuel from an injector that is activated at that moment but insignificant, you can stab that peddle all you want and nothing, now a leaking injector(s) can flood the engine, a malfunctioning TPS or other sensor can contribute to an over rich condition, combined with old, weak ignition parts and you have a flooded no start condition so it is possible to flood a EfI engine.
Pressing the go peddle to the floor, just like a carb'd engine, shuts off the injectors when cranking to clear this, I believe it even referred to as a 'clear flood procedure '.
This is based on what I have learned here and personal experience and not based on any actual mechanical certification so don't call me as an expert witness in an automotive related court case

manicmechanic007 said:

won't run the carb out of gas, and the fuel pump is still pumping while cranking the engine over

Click to expand...

I was referring to pumping the peddle engine off, key off (not cranking)
While both 'technically ' are correct, you still have to have the last word