First thing is to take a look at the caps & rotors. If they're not new or in very good shape, you need to bite the bullet and replace those parts. At least then you'll know where you stand ignition-wise.

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"If God had meant for us to walk, why did he give us feet that fit car pedals?" Sir Sterling Moss

Michael
2014 E63S Estate
2006 SLK55
1995 E500
1986 Porsche 944 turbo