I have a 1997 E420 with about 120,000 miles. When the car is in drive, the RPM drops very low and just before it stalls the car seems to catch itself and surges the RPM up. This cycle repeats continuously every few seconds until the gas is pressed or the car is placed in park then the car drives and functions normally. This problem has been going on for some time and is really aggravating especially at a red light when the car almost stalls then lurches forward unexpectedly. I recently had a mechanic take a look and they thought that a tune up would help. After changing the plugs, fuel filter and air filter, the problem was still there. They then thought that the problem could be with the computer air regulator which they sent away to be rebuilt. Now with the rebuilt air regulator, the car seems to run at a higher idle (at about the 10 mark) and does not come close to stalling but the rpm still fluctuates a little. However, as soon as you turn the A/C on the rpm drops back down and the almost stalling problem is back. When the A/C is turned off the rpm goes back up and the problem goes away. I am running out of ideas and don't know what to try next. Any thoughts?
Thanks,
Jon
Thanks,
Jon
