2000 ML320 throttle/idle trouble
 

I am having trouble with my 320. When I start the car it idles fine. If I push the gas peddle in about 1 inch it accelerates smooth. If I push the peddle to the floor the car will not accelerate and will jerk like it is down shifting. Then the car will idle rough and hardley make it up to 20mph. If I turn the car off and back on it will be back to idling fine and running the same. I can never push the peddle all the way to the floor. Does anyone have any ideas of what the problem is?

Thanks

Yes, it sounds like bad CPS crankshaft position sensor. Do you have your check engine light on? If yes, then your engine is misfiring on hard acceleration and will limit engine output because it's unsure of the crank position and running on 5 or 4 cylinders untill you shut it off and restart it, which will reset the computer. Check the stalling/starting problem post that I have just replied to.
You could also have faulty trottle position sensor and clogged EGR valve tube but I doubt that. Go to any autoparts store, have them scan it for free and post your codes.