99 SL2, AT, just under 130,000 miles. Recently has become difficult to start.
Engine cranks fine, sometimes fires immediately and runs perfectly, but about
80% of the time it will fire immediately and either die within seconds, or run
very rough for ten to fifteen seconds. When it dies, it's difficult to
restart. Seems to behave better when the temperature is below freezing.

Spark plugs are new, less than 1000 miles. (Problem occurred before the spark
plugs were changed.)

Any suggestions would be greatly appreciated.
TIA