Surging Idel
 

When driving my 1987 420 SEL the other day I noticed that when the car is at idle their is a slight continues surging of the rpms along with a coinciding fluctuation in the oil pressure gauge.

Any Ideas!

Thanks,

That means you need to align the fuel distributor. Also check for vacuum leaks.

On a 420 it means that under load the ignition is breaking down.Time for new plugs, leads, cap and rotor.

Thanks for the advice it LOOks like a tune up is at hand it's just the price of everything that has held it off till now!

Could be vacuum leak
 

I just had my '03 C230K fixed. It had oscillating rpm's during idle. The mechanic sprayed carburator fluid around all hoses. Then he sprayed it near the intake manifold gasket, and voila...He replaced the gasket and the car is idling fine now. $7 for the gasket, $444 for labor.