Chugging when driving. Okay when it is cold but soon as it gets warm it is as though it is firing on 3 and not all 4 spark plugs - Please can anyone advise as I think I may need some copper spark plug leads. I have placed some new bosch spark plugs in with copper centre, no oil leaking anywhere so baffled - Your help is appreciated

mark dunning, March 2009

possibly coil breaking down when it warms up??

sonic, March 2009