Dan as you probably know 50 psi is low for that system and then you get a good psi out of it on the next start up, put a fuel pressure gauge on it it could be a bad regulator and just because the fuel pump is new does mean it is good. Your timing should read around 20 to 17 degrees before top dead center it should never read 0. If it is at 0 your PCM is not advancing your timing and it can create a lot of problems.