Have the coil ends, not the coil packs replaced..do it yourself...3 coil ends i believe, cost is like like $10-$15 bucks each? Very cheap, see what happends.
wiring harness could be a possibility..very expensive.
As to the cruise control, I had the same problem. It turns out..believe it or not the cause was I had different brand of tires on the front and back.
Sounds like BS? I kid you not. once I bought new tires of the same brand it worked again. The dealership also swapped out new rims and tires from the showroom C43 to test it out and it was the fact that I had different brand of tires on.
1997 Silver AMG C36
OEM Advantegarde Grille
OEM Clear Corners
W210 Blinking mirrors
Zender Rear Lip Spoiler