Tough to say, but you could have an injector sticking open from bad injector or ecu failure. I wouldn't run it until you figure out as you could hydrolock the motor if it's dumping enough in. Not to mention the increased wear from the diluted oil.
I had this happen to me once on an 5.0 Mustang I used to have a long time ago. It was that particular pin on the ECU that failed giving it constant power and holding the injector open.