Pull your spark plugs and check them for oil fouling. I remember someone had posted about this same problem a while back and it turned out to be worn valve stem seals. That would not be unlikely on an engine with 177k miles on it.

__________________
"It's not about how fast you can go, but how well you can go fast."

Bob in Richmond

'97 S320 (LWB), Ruby Red Metallic, 73k miles
'97 S420V, Smoke Silver Metallic, 155k miles