Hard start when warm and temp gauge issues
 

I have a 94 E320 when starting after sitting overnight the car starts almost immediatley, after warming up and shutting the car off, it takes depressing the accelerator partially or fully to start the engine.

I also have a problem with the temp gauge bouncing from normal temp 80C to over 120C , the needle can be pegged when starting the car in the morning, I have disconnected the sending unit plug and the needle drops to the low point on the scale, when plugged up again the needle pegs at the max once again, while driving down the road the needle will either be normal or be pegged at the 120C mark again, the needle bounces back and forth between 80C and the next line, (guessing 90C) at times. I have changed all sensors on the thermostat housing and flushed the cooling system, replaced the thermostat and viscous clutch. I have checked the actual coolant temp, the highest I have found it is 185F, on a 100F degree day. any suggestions will be appreciated.

Sounds like you are running lean once warmed up. Do you have an air/fuel mechanical mixture on that car?