2005 Mercedes Benz E350 mileage: 30,000. When it is not freezing outside, after my car is warmed up to normal operating temp, if I shut it off and let it cool down part way, it doesn't want to start. It acts like it is being choked. If it cools completely, or if it is still at full temperature, it starts fine, but when it has had 20-30 minutes to cool, it acts this way. It will run very rough, when it does finally start for about 30 seconds to a minute. Any thoughts?
An internal fuel leak, possibly a fuel injector or fuel pressure regulator, could be causing your problem. Remove the vacuum line to check for the presents of fuel. If so, replace fuel pressure regulator with new to repair problem.