Hi, just bought a 1993 E220 W124, and in the last week it has been giving me a bit of a head ache. it would for no reason start shuddering, as if its not firing on one cylinder, but if the car is switched of and restarted, it runs normal. Revs also pick up to 1500 rpm. have changed the spark plugs today, as i thought one might be faulty . ( disconnected each plug lead while it was in its "shuddering state" ) and found one to be "dead" cylinder no 2 But the problem returned a couple of hours later. this time on cylinder 1 and then on cylinder 4. What really confuses me is that, once the car is restarted, it returnes to normal, for a time.... have noticed that if sudden braking / stopping is done it also "misfires"