Have you also checked the timing, plugs, points, air and fuel filters? Does the engine idle OK, run smoothly? Any strange symptoms, like short on power or hard to start?
2003 Firemist Red/grey leather SL 500
2015 Palladium Silver/black mbtex GLK 350
1987 Smoke Silver/burgundy mbtex 300E Sportline (SOLD)
Click to see 87 300E