1999 Buick Regal 3.8 (K) No start condition?

Ok here's the deal. I have a 1999 buick regal with a 3.8 liter non supercharged engine. Here are my symptoms and what I've done so far:

-Engine turns and intermittently wants to fire but doesnt. But mostly just turns over

-I have good spark on all 6

-I have good injector pulse

-I show a fuel pressure of about 50 psi

I have replaced coil packs and module, crankshaft position sensor, wires. I also replaced the fuel filter which was plugged almost solid.

In the beginning it died while driving. It started misfiring badly and wouldnt restart. Now I'm here trying to figure out my problem. I'm almost thinking fuel pump, but I cant seem to find the proper psi online. And I dont want to make a 300 dollar guess.

Also, the only codes I was showing was po300, multiple cylinder misfires....as if I needed a computer to tell me that. LOL

Thanks for the help.