Volvo Repair: Hard starting, fuel pressure regulator, coolant temp

Question
I have an 89 760 B280F v6.The car starts right up when cold,but when you shut it off and try to restart it doesn't want to start.Only after the engine is totally cold again will it start.I recently did a valve job on it replaced plugs ,wires ,cap ,rotor.Could it be cold start valve.I've replaced just abut everything I can think of.The car has been doing this even before I redid the top end.Any ideas?

Answer
Ken, it may be a few things.  I would start by checking the fuel pressure regulator.  Also the coolant temp sensor may be another culprit.  Could be dumping too much fuel.  May also be a fuel pump check valve.  You should do a pressure test on it.  Roger