I have a 1992 500SL with 75000 miles if it sits for more than a day it starts right up but once it is started and warmed up then shut off, if not restarted within 10 min. it has to be cranked over for about 30sec. or longer before it will start. I have had the fuel pump and presure checked and vac. lines. HELP!!

Sounds like you could have vapor lock due to your fuel accumulator going bad. Do a search on these two and you will find lots of information.