Our ’02 ML 500 with 115K miles, intermittently hesitates for a second or two when the accelerator is pushed. It is like there is a delay between when the accelerator is pushed and when the throttle is opened. Pushing the accelerator further does not seem to make the engine respond any quicker. There are no lights and no engine codes. The first time this occurred, the service folks replaced the Accelerator Pedal Sensor (Accelerator Potentiometer) and serviced the transmission. The truck ran well for 1,500 miles, and then developed the same symptoms. The second time, again with no lights or codes, the wizards again replaced the Accelerator Potentiometer – they claimed the first one suffered infant failure. Now we have approximately 600 miles since the second potentiometer was installed and the symptoms have returned. The professionals do not seem to be able to isolate this problem. The fuel pump was replaced 11 months ago. Any observations will be sincerely appreciated.