WANT '71 280SEL and Tim's__Benz are one and the same?

I'm guessing you're looking at and pushing on the air flow meter. Kinda spongy and when you push it down the engine dies? If so, it’s partially open because the throttle blade beneath it is partially open as well. The throttle blade controls the amount of air allowed in, the air flow flap is measuring how much air is flowing by. If you push it open, it thinks air is causing it and it will dump more fuel in to match. If the air isn’t really there because you fooled it, then it chokes itself out on fuel. With the engine off, gently push the airflow flap down and you should be able to see the throttle blade. I bet it’s stuck slightly open… At least I hope so, because I can't think of what else it could be.