Regarding the 2000 E430 4MATIC I recently purchased (119,000 miles), I noticed there is a very slight bumpiness from time to time at idle just above 500 rpm (the normal idle after warmed up). This is why I contemplate changing the plugs (or having them changed). This is intermittent, meaning it does not happen very frequently at all, and is more of a skipping or missing, i.e., impression is a misfiring from time to time. And, it is very, very subtle, not rough or dramatic. I am perhaps being overly sensitized by this as the 300E 4MATIC (1992 with 253,000 miles and still running) I have rarely if ever had a rough idle.

There is also a light "clatter" I can almost say it is the right front cylinder because if I put my ear close to the engine this is where it is coming from. I had failing or sticky lifters in the 300E 4MATIC but the clatter on cold mornings (was actually a different sound) would go away after the 3-5 minute warm up period I am accustomed to before putting the car into gear.

I also believe this clatter tracks the rpm's such that when you rev it or accelerate the rythym (speed of the clatter) increases proportionally. I put two tanks of premium fuel through it so far and on last fill up treated it with a pint of Sea Foam (which I never ever did in the 300E by the way), because the guy I bought the 2000 E430 4MATIC from put regular gas in it for the 600 or 700 miles he drove it .

He said physics say its the same thing to put 87 or 93 . I said .

Anyway, to avoid any major engine problems, if the Sea Foam treatment and the premium gas does not blow out the stickiness / clattering sound, what are my options to have this "diagnosed" without being fleeced? Or is there any other self-help I can engage in without hurting myself?

My ultimate plan is to bring it to a dealer and have them perform the full $208 pre-sale inspection as if I am going to buy a new one from them to make them tell me everything it needs, and then take it to my German mechanic and see what he says about it and start fixing anything major.

Any thoughts or ideas. Thanks, CJ

__________________
CJTucker