An injector gets stuck open?

I'm having a fueling issue and I've tried everything and I can't find my damn problem.

Symptoms are: when the car gets hot, or has been run moderately hard, the fuel pressure goes nuts. It will go from 40lbs to 30 back to 40 drop slowly to 20 back to 30 then back to 20 then continue to drop and repeat a process of going up and down until either a) the car dies or b) i can romp on it enough to get the pressure back up, but as soon as I'm either idling or running at a constant speed it messed up again.

This doesn't happen every time I run the car just every now and again...enough for me to not feel comfortable enough with the car to take it on anything longer then an hour cruise or so...

My roommate said that it could be an injector sticking open and the other injectors compensating by dumping fuel. In return my pressure drops because all the injectors are just flooding the engine.

Could this be the case?

I have replaced the fuel pump THREE TIMES and have bought and installed the fuel pump hot wire kit which runs direct voltage from the alternator to the fuel pump. So I KNOW it's not in the wiring.

HELP.

 

Sounds like a fuel pressure regulator going bad to me.

 

I thought the same thing, so I replaced it a month ago...no dice