I recently bought a 2000 C280 and I love the car. From my notes, the 98 is second year for the 722 transmission so hopefully it is sorted out. The fixes seem to be well known. The 98 is the first keyless and the better antenna so that is good. Check the harmonic balancer and if it is part # A112 035 00 00 or A112 035 06 00, or looks worn (not spinning smoothly) it needs to be replaced.

glenmore
1991 300CE
1990 LS400
2000 C280