500 SL strange hesitation/sputtering in humid climate
After setting for a week in humid climate the car starts and runs fine for 3 to 5 miles then it starts hesitating/sputtering (about the time it reaches operating temperature) for next 3 to 5 miles after that it runs fine. No problem again until it is not driven for a few days. Wiring has been checked, gasoline treated, fuel filter changed. Mechanics I have talked with do not have a clue. Car is garaged adjacent to Gulf of Mexico. While it is having the problem the engine runs reasonalby well while in park or nuetral but under load is when the problem occurs. Help please, I am very fustrated.