Originally Posted by Chefboiali
Man... I don't know. I DO think, however, that you have an opportunity get closer to your motor by looking at it as though "something" isn't where it's supposed to be. ie., spark plug wire, etc. Sounds like your car is trying to suck air threw a straw with a hole on the side. Sucking harder and not achieving enough for it's effort. I'm sure someone here knows where you should start, but I'd try on my own first. Maybe start with connections that you can reach without getting under the car first.
****Edit**** Maybe a motor mount?
Woops forgot to mention it only does it when the clutch is depressed. If the car is in neutral and my foot is off the clutch, the car is perfectly normal. The more I depress the the harder the pedal jumps back and the louder and harder the engine jerks.