My 1996 SL500 has 220,000 miles and runs great. However... At between 1000 and 1500 RPM when the engine is 'floating' (not accelerating or decelerating) it feels like it loads up about every 10 seconds. The tach drops a few ticks and then it comes back up. In my carburetor days (if you remember what those are), I would have leaned up the mixture. As soon as I give any acceleration, it snaps to attention and runs smoothly. Is there a sensor going bad? I am not getting any codes on the computer.

 

get some spray carburetor cleaner and spray around your vacuumhoses and injectors while the car is running. if the idle changes while spraying, you know that you have one or more vacuum leaks. before you start messing with anything, checkfor thoseleaks first.