I recently bought a 2000 MB S500 that seemed to be in good condition but now has starting issues. A couple weeks ago it started taking longer and longer to get fuel and start, until one day after it worked in the morning, it wouldn't start in the afternoon. I had the fuel pump and fuel filter replaced, and it worked just fine for awhile, but today it happened again. It worked fine in the morning, but after sitting for just over an hour it wouldn't start again. I let it sit another 2 hours and it struggled, but then started. My friend said it might be a vapor lock issue. Any thoughts?