Do you have a spark? At the coil lead? At the plugs?
Is it getting fuel?
Can you warm the garage up? Ice, water in the fuel?

High idle might be the coolant sensor that keeps the idle up until it warms up.
Battery voltage? Does it turn over fast?

Gotta be something simple if it just happened.

__________________
1991 300 SEL
218,000 Km

"Xsbank's rules of mechanical intervention: Always go for the easiest solution first; 90% of what ails a gasoline engine is ignition; After that its all a WAG."