Please help, my W reg ML320 is badly misfiring! It has been going on for months, I pull away and it goes into limp mode. I turn it off and the problem sometimes clears. On over-taking, it sometimes loses powere and this morning i nearly had an accident. We replaced the oxygen sensor and the problem still happens. I took it to the garage and the diagnostic was 'ECU random misfire'! We replaced the MAF sensor and it improved for a while but now it is bad again. It is worse in damp and cold conditions. It is driving me nuts!! Please help!