1992 W250, 200k miles, 5 speed, 12valve, intercooled.
Ok, heres my problem: when I first start it up in the morning everything is fine. I have good power around town and down the road. But when I get about 8-10 miles out and temperature comes up to normal, it gets to running rough. I can only top out about 40-45 mph but then it bucks a few times and I have full power. As long as I don't let off of it, it runs fine. As soon as I slow down some, it looses power again and takes a while to build back up. I notice when I get back from the drive, the engine idles rough. Does it sound like the injector pump or something electrical? What exactly does the crank sensor do? I opened the electrical box on the drivers fender and it has about 14 years worth of dust in it. I am getting good fuel supply from the tank, also just replaced lift pump thinking that was the problem. Bled the injectors and changed the filter. Anyone had this problem before?