My 94 S320 is trying to drive me crazier.

for the last few weeks, the car runs hot in stop-and-go driving. it's usual temp is right at 100deg, which i see from the forums is rather high.

when in stop and go driving for a bit, the car rises to 110, then past if it's really hot and i stay in town. when i get moving more it cools back down to 100.

the car seems to have no problem with interstate driving, remaining at 100deg.

the fan clutch seems fine (can't stop the fan running, or even slow it down), and the auxiliary fans are running.

if i turn the A/c off, the car runs less hot. it's around 100deg. outside every day, and the car minds night driving less (when it's around 80).

I see no sign of sludge on the oil cap, and no milkshake in the coolant bottle, so i'm hoping it's not a head gasket problem.

i'd appreciate any help you guys can offer to get this fixed.