My Gf's 94 vtec sohc makes this really annoying loud rumble when i start it. Then the idle drops, revs up and then drops again over and over. It drives and all but it makes this noise like it's skipping and there's not enough fuel. Even when i drive it i step on the gas pedal and it hardly goes anywhere. I changed the spark plugs, spark plug wires, and the Idle Air Control, and still does it. What is this problem? There are no engine codes whatsoever. Could this be a fuel regulator issue? What is a fuel regulator issue, how do you know when it goes bad? Or could it be bad fuel injectors? It almost sounds like 1 cylinder isn't sparking or what not. If anyone knows how to solve this problem, please let me know. thanks.