I purchased a low mileage (121,000) 1990 240 sedan a few months ago. Now that the weather is turning colder, I am having some cold start issues. The car starts right up in the morning, but it acts just like a carburetor with the choke stuck closed. The engine runs rough and emits black smoke out the tailpipe. If I hold the gas pedal down for about 5 or 10 seconds at what I'm guessing is about 1500 rpm, the engine will "clear out" and then idle fairly well. Any ideas as to why its running so rich at the initial start up? Faulty cold start injector??