Lately my van has developed a starting problem when the engine is warm.  It fires immediately when it is cold or if it has sat for an hour or more.  It runs perfectly otherwise.  If I shut it off and try to start it 15 minutes later, it will crank just fine, but it does not fire.  If I turn off the key and turn it back on, it starts right up.  There is no sputtering, etc., as if there is nothing wrong.  Any ideas?

  I'm leaning toward fuel pump relays or the coil, but I want to get an opinion before throwing $$ at it.  I also notice a large price variance in coils.  What is the difference?  BD appears to offer a lower cost one than other places.