I have a 1998 E300TD with 313k miles. About a month ago it started taking longer (15ish cranks) to start when warm (coolant anything above like 50°C), but starts fine cold (about 3 to 5 cranks). I have replaced the fuel prefilter screen, battery and crank position sensor but the symptoms still persist.

I do have a fuel leak from my fuel thermostat (next step I think is deleting that), but its had that leak for about a year and hadnt been having these issues before. Anyone else have this problem and know what to try to replace next? Maybe a relay?

Thanks so much in advance!