Mercedes Benz repair: High idle on 1985 380SL, fuel pressure regulator, fuel pump relay

Question
I have recently purchased a 1985 380SL with unknown miles. The engine runs great, but on occasion it idles at 2000 rpm (warm or cold )I am wondering what to check to locate the problem. I don't hear any obvious air leaks, but I'm not ruling out a vacuum leak. Any help will be appreciated.  

Answer
Need miles upon vehicle, any guess?
Is there any corrosion in engine compartment?
The list is huge, without rough total miles on vehicle:

Alternator
Bad fuses
Bad wires brittle/broken/shorted.
Corroded wire connections.
Cold Start Valve
Cold Start Valve Gasket
Computer water Temp Sensor
Frequency Valve
Fuel Distributor O-Ring
Fuel Injector
Fuel Injector Seal
Fuel Pressure Regulator
Fuel Pump
Fuel Pump Relay
Idle Control Unit
Idle Control Valve
KE Control Unit
Overload Relay
Oxygen Sensor
Reference Sensor
Thermo Time Switch
Throttle Body Gasket
Vacuum Advance Unit
Voltage Regulator
Warm Up Regulator