Pulling the spark plugs and checking what one if any look different than the rest may shed light on what cylinder is giving you the issue. The deposits or lack of can tell you a lot about your engine and is easy to do, even if you only have simple tools at your disposal. If you find particularly sooty, Wide/ narrow gap, worn plug or even a fuel covered plug it gives a hint where to look. That being said the fuel pressure test you did makes it look like a leak isn't your issue as it was holding pressure without leaking down. While you are looking at the spark plugs check the gaps and condition of each plug to eliminate the possibility that your plugs are the issue.

 

I'll get a chance this afernoon to take a look at the plugs. I had checked them after the top end/cat cleaner I ran through it. I had also checked gap at that time. I have put a couple 100 miles on it since then. Maybe they will show something now to narrow it down.