Hi all, I have a Mercs 300SE year 89, low milage 50,000 miles, automatic transmission. I do not drive the car very often. When I start the engine and drive for about twenty minutes the engine will misfire and die down. I have to wait for about 20mins in order to be able to restart the engine, because the engine will not start even if I try to do so. I notice that it is better for me to wait for that period of 20min in order to succeed.
After restarting the engine I have no problem at all for the rest of the day.
What can be cause of the problem?

 

any ideas please?