1990 300SL, 60k miles: Cold starts fine, runs smoothly, no missing is apparent at any RPM. Once up to normal operating temperature, continues to perform smoothly. BUT, if stopped and the engine turned off, can not complete a successful warm start unless left to rest for about 30-45 minutes. Without the wait it sputters, coughs and then dies. But, after waiting another half hour it starts instantly and runs smoothly until turned off again. Then the same wait is required for the next start. It has good spark and acts and feels like a fuel mixture problem. Online I have learned that somewhat similar symptoms have been attributed to coolant temperature sensor issues, rotor and cap problems, vacuum leaks or the fuel pump relay. This car is in a remote location 250 miles from the nearest Mercedes mechanic. So, its up to me to fix it. Where is my best bet to start for a fix based upon these symptoms? I am not a serious mechanic but am capable of replacing parts. Any help or direction would be appreciated.