i just bought a 1989 190e 2.6 auto with 170,000 in good condition iv had it a week and seems to use a bit of oil and ran fine since i bought it, till today it had a rough idle and accelaration so i bought some bosch plugs and well i took out the platnium2s i noticed all of them had alot of buildup almost bridging once i put the new plugs in it ran smooth and idled smooth . does any one have any advice on common problems on 190e and if thats normal for plugs to have alot of buildup or whats causing it?