300SE 1991 will not start when hot.

[Digtyler41]

Hello everyone, its great to find people online who love Mercedes.
I have owned many over the years, starting with a 1969 280SE.
I now have a 1991 300SE which has run very well until a few days ago. I need any help that you can give me.
My problem is as follows. The car will start and run very well to the shops about 2 miles away. After I come out and try to start car it will not start. I did eventually get the car to run by putting the accelerator peddle to the floor and holding it there. It reluctantly started after about 20/30 sec cranking. On the way home it would misfire/stumble it I put the accelerator peddle down to hard.

This sequence will repeat if I let engine get cold. I have tried pulling of plugs from Temp sender and what I think is the idle control when engine is running and it makes no difference to the engine running. I am at a loss as to what could be causing this. I need desperately need any help that can be given.
Cheers, Brian.