My 420 SEC has some problems during the warm up cycle as follows:
The car nearly allways starts first time from cold, whatever the weather or temperature.
Starts idling at about 1500 RPM, then quickly settles down to about 800 RPM. When fully warmed up, it idles at about 600 RPM in drive, with the footbrake applied.
Towards the end of the warm up cycle, there are instances of hesitation/loss of power to varying degrees. Occasionally it has stalled. After stalling, it is very difficult to restart. Once fully warmed up, the engine runs fine apart from occasionally the idle will increase to 1500 RPM, then drop to 600RPM.
After the car has warmed up, and then parking and switching the engine off, and then coming back to the car after between 15 and 30 minutes it has been very hard to start again.
The car has new plugs fitted, and the leads, distributor cap, and rotor arm have been checked and are all ok. The fuel tank has had two cans of injector cleaner added to it as well. Also the fuel filter has been replaced. I have cleaned the idle control valve although it did not look dirty.
Any suggestions regarding which part(s) need checking/replacing?
Thanks in advance,
John Hughes