the answer to my intermittant "stumble". Man when this car runs right it sure is a pleasure. Ran great all day Monday. Tuesday first half of the day no problem and then 10 minutes after turning car off when out to run an errand and in the first 5 miles the tach indicated erratic behavior illustrating the car's "rumbling/misfiring". This time it did not stall out - I only had to keep constant pressure on the accelerator and "drove through it" till it smoothed out (20 seconds). I picked up a set of new wires. Will install tonight. Have checked all wiring that is otherwise easy to check. Also sprayed all connections with electrical cleaner with no change. Will keep all informed. I'm starting to lean towards a fuel delivery problem. may have to purchase an hour of Mercedes diagnosis time.