'91 300SE hesitation- possible clue ?

[microtoad]

I have been having intermittant hesitation problems on my car. Sometimes it seems like the accelerator pedal is not connected to anything. Yesterday I was out shopping all day and the car ran perfectly. Late in the day I decided to wash the car to get all of the salty road spray off. I went to a you wash it place with the hand held sprayer and tried my best to get the car exterior clean as well as spraying the wheel wells and underbody. When I left it started right up but as soon as I turned onto the main road I noticed the hesitation. It was worse than ever and I was worried I wouldn't get home.

It's like when you have a car with a carburator and the accleration pump is bad. You step on the gas and nothing happens (no squirt of fuel down the venturi's), then it slowly builds power until you are driving normally. The little vacuum gauge in the instrument cluster swings over to to full right so it appears the throttle is opening up, just no fuel. I assume water has gotten in somewhere. Any suggestions on the where to look for the offending component/connector ? I thought possibly the idle control valve. It is more towards the front of the engine where it can get wet. Possibly the fuel pump connections ?

One more clue. Every now and then the car hunts for the right idle point. The tach needle tends to bounce up to 1300 then fall to 600 then bounce up to 1300 and so on. Slowly the oscillations dampen and it finds the right idle at about 600-700 RPM.

Any suggestions to point me in the right direction would be apreciated.