My new (to me) 1988 300CE was idling a bit rough, so I changed out the plugs and ignition wires. The car has 70K miles on it, and the wires were obviously original. The plugs I pulled out were Champions?. Installed new Beru wires, but could not readliy find the recommended Bosch copper core H8DC plugs locally, so I put in a set of NGK substitutes. It ran decently for a 100 miles or so, then the rough idle came back. Pulled the plugs again, all were black and sooty, especially #s 1 and 3, which were oily and fouled looking. I picked up a set of slightly hotter Bosch H9 DC 0 copper cores, and put them this morning. The H9 DC 0 seems to be the plug of choice on this forum. My question is, should I be worried about the condition of plugs 1 & 3 at this point, or just run them awhile and see what happens? Is this fairly common with these cars? Thanks for the great advice as always. Don

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93 190E Sportline (RIP) (45K)
92 190E (Xferred most Sportline parts to this body)
88 300CE (71K)

And the Jeeps:
01 2WD Cherokee XJ (35K, Mama's grocery/kid hauler)
91 4WD Comanche (300HP stroker)