idk man. mine used to do that, but its something that came and went. i did a tune-up one day, changed the plugs, wires, cap and rotor, never happened since. but i know exactly what you are talking about. I really think its a fuel/ spark problem. this sounds dumb but i want you to try it and tell me what happens. turn your car on, and then disconnect the connection to the head temp sensor, that should send a signal to the ECU to make the fuel injectors to maximum duty cycle. then rev the engine and see how it runs. In theory it should run like crap, but in your case it may just work.