1986 420 SEL rough starting problem

Have an intermittent problem when starting this car. Car starts without problem 70% of the time. Instant ignition, idles perfectly, impossible to tell if engine is running. Other times the starter must be engaged for ten or more seconds before the engine even tries to start. Sometimes 3 or 4 attempts must be made before the engine fires. When it does finally start at these times, ignition is slow and it seems to be firing one or two cylinders at a time before it finally catches and idles properly. Problem arose immediately after having a new fuel distributor installed. Seems to occur mostly after driving for several miles and stopping (at a restaurant for example) and then starting the car again. Problem seems to occur when engine is hot as it can set all night in my garage and in the morning it will start without problems. Fuel distributor was adjusted with a "scope" and set to factory specs. Replaced one fuel pump on this car because of a small leak at the pump. Did not replace second fuel pump. Car has only 130,000 miles and is in pristine condition. Everything works and it is a pleasure to drive. Any ideas on where to start would be appreciated.

Forums

Chassis Model Number