I have 500 SEL 1984 with 97K miles on it, recently at start up it is taking a little longer to turn over (6-8 Seconds) additionally intermittently it will go from idling its normal 600 RPM to 1500-1600 RPM and will not kick down. It will continue to idel this way for some time. This is an intermittent problem does not occur every time.The engine is spotless all linkage is clean and working properly. Up until thNo major changes have been done to the engine to cause this to happen. Does anyone have any suggestions it would be greatly appreciated.