Ok guys here is an issue I just discovered. About a month ago I replaced the plastic fuel filter on my 86 300SDL because the engine was hesitating. This fixed the problem, I also purchased a primary fuel filter which I have yet to install ( didint know which one was bad ). So I have not driven the car in a bit and went out to start it and the battery is dead. So I jump the car and drive it most of the day ( ran fine no problems) Well I was about 30 miles from home when I was on the freeway going about 70 when the car started what I describe as hesitating. It would maintain 70 but it was almost like the engine was almost like a fuel / air starvation problem as the car seemed like it was hesitating to keep that speed. I get home and the car is running fine , engine will rev and run fine but a few days go by and I try to drive the car and it is doing the same thing this time at a lower speed. It will start out in first and right when it shifts to second the engine cuts power ( still runs and sounds fine ) but i cant accelerate because the car almost feels like it si going to stall. When I stop the engine runs fine and starts off fine. What should I check? I have not checked the air filter but where should I start? Any thoughts?