My 400E has suddenly started to exhibit some strange behavior.
The car was running perfectly until a couple weeks ago when I started it up and it immediately began running roughly. If I suddenly press the gas pedal to the floor, the car will stall. If I put the pedal about halfway down, the car hesitates severely and then will accelerate normally.

This is not in itself very strange I guess but I have discovered that if I turn the car off and restart it 2 or 3 times, I can get it to perform normally. I can now tell by the way the car initially starts....if it runs rough upon starting then I just turn it off and restart until I get a smooth start and then it will run fine.

Can anyone suggest what might be causing this issue?

I'm thinking it might be a wiring harness issue but might I just have a bad fuel pump relay or filters or wires or plugs?

The car has 100K on the clock with 2 year old caps, rotors and plugs (20K on these). Original wiring harness and original plug wires.

Any help appreciated.