Heck, make sure your battery is good under load. Check your motor oil. If its too thick for the weather, it makes it tough to crank...
Also try glowing the plugs twice before starting, especially in cold weather.

Best of luck. And what others have opined...

__________________
1979 300D 220 K miles
1995 C280 109 K miles
1992 Cadillac Eldorado Touring Coupe 57K miles SOLD
********************
1979 240D 140Kmiles (bought for parents) *SOLD.
SAN FRANCISCO/(*San Diego)
1989 300SE 148 K miles *SOLD