Starting and idling problems

That seems a lot like what happened to mine after a few miles. I have a fuel pressure gauge in my system so I could see it was a fuel pressure issue. What I thought was a pump that couldnt hold pressure was actually a bad fuel filter/regulator. It literally had 100 miles on it when it crapped out. Motor would idle poorly, with fuel pressure so low it didnt even register on the gauge. I was baffled at how it even ran.

Get a pressure gauge on there for sure, otherwise you're just chasing your tail.