I'm having an issue with the idle and acceleration on my 1997 318i. The rpms rev between 1 and 1.75 when idling and when I tap the gas the car seems as if its chocking for air and the engine gets week almost till it shuts out. When in drive the car rolls with my foot off the break. but as soon as i hit the gas it get weak again. I pulled on the throttle from under the hood slowly and its revs pretty strong. but if i tug on it abruptly or suddenly the car sounds as if its not getting enough air and does the power loss and threatens to shut out thing. It seems as if it got a little stronger as i test drive it more and more. But anytime I put pressure on the gas pedal suddenly it shuts off. I can only drive on flat surfaces. If i try to go up a hill it shuts off. What the heck can this be.