If it is vapor lock then the car should have started once everything cooled down. Get a FSM from http://carfiche.com and do the tests for the ignition system. Also check out Blue's Tech Tips for the EFI bible and some other good info. Check fuel pressure, spark, timing, injectors, fuel pump, etc... There's many things that need to be checked that you haven't yet. The L series engine is actually a very very reliable engine so long as it's well taken care of.
Also, this should be under the S30 forum, not the non tech board.