Another Hot Start Issue 94 e420
 

I just got back from a trip to yellowstone. While there, the e420 (turned 106k) would only start when hot if the gas pedal was all the way down. It idles fine after starting, no stalling, no power loss or surging when driving. I have searched the posts and none seem to relate to my particular year, model, problem. Before I started diagnosis I was hoping to get some advise on where to start. So for starters, how do I determine if it is a fuel issue or spark? The dist. caps & rotors have not been replaced for at least 20K, so I will be ordering those and plug wires today. The PO does not have any tune up records, so they could be OE for all I know.
Thanks for all the help.