hi, can anyone help me with this query? i have just bought a 1996 w124 auto e200 estate and when in the park or neutral positions the engine revs up to 4000rpm and then starts to misfire, however when being driven it revs right up to the red line with no misfiring. is this some kind of safety feature or do i have a problem. if it's a problem can anyone tell me what it is. thanks in advance for any answers, rod.