Hi All, this car is a 1993 500SL with only 23,000kms on it. Ran fine when I got it and still does if I drive it every day. However if I leave it sit for more than 3 days, it runs very rough at idle and misses badly for about 20 min when started.

It warms up in 10min so I don't think it is temperature related.

Somebody said stem seals but there is no white smoke at start up. It has been suggested to change the coils. I have changed filters and run injector cleaner. If anyone has solved this please let me know. I took it to the dealer the other day while still missing a bit (mainly at idle) and they put it on the computer but said it was fine aaarrrgghh

Any ideas much appreciated.....