well buggor34 service my car for me (thanks mate) this included new oil 4100, oil filter, fuel filter, new plugs and also cleaned the AAC and FIXED no more missing im so happy, sorry i couldnt be more helpful in diagnosing but one of the above fixed me problem, we are thinking it was most likely the plugs to be honest as the others were totally screwed that or AAC which wasnt really dirty at all.