Just picked up an '80 300D w123. When I start it up it sounds like it's only hitting on 4 cylinders. It also hesitates slightly of idle. Second is the trans. It shifts if you let of the gas, or after it gets warm it seems to shift to often. I figure I've got a bad injector, and a bad modulater valve in the trans. Any other suggestions? Any place that will have the parts at a decent price?

This thing's a dog compared to my 16v.