the elastomer coming out of the crank pulley wont cause a specific misfire. if it fails the pulley comes apart and causes massive damage. the crank pulley is keywayed to the crank so it doesnt move once installed to 150 ft/lbs plus 90*.
its easy to see if the pulley is wobbling start the car at idle and watch it. try oediscountparts.com and search under the slk 320 for a n/a car or slk32 for the srt-6 cars. my oem pulley was about 260$ shipped but i think you have issues elsewere