I have a 1980 300CD with 132K miles that has a irregular missfire when cold. It does not go away with increased rpm. However, it is completely gone once the engine is warmed. This only takes a few minutes unless the ambient temperature is below 30 F or so. Valves have been adjusted recently, one can of straight Diesel Purge has been run through it, and I've attempted many Italian tune-ups. Oil usage runs at approximately 1 qt. per 1000 miles. Does anyone have any suggestions where I should start my search?

Garth Frazier