fuel issue at port

i have a 91 grand voyager 3.3 and noticed starting issues with fuel ,primarily at start up or if cold.It takes a little longer of a turnover to start than it used to.
I noticed just yesterday after starting it wouldnt remain running until warmed up then no issues on road but sometimes when restarting when motor is warm it would take a extra prime for a start..Runs fine after a warm start .
I changed the fuel filter and also looked at the fuel rail cap and found it leaking tad there.I used a tire tool and tightened it but not sure yet if that will hold up

I did look at pressure regulator and it is holding pressure .

Can i replace the o ring to it inside the fuel rail port or is it not accesable?

What is the pressure suppose to be for this if i do a test?

Also what else might i check out?