WHat is the correct procedure for testing the fuel pressure on the L67?

Im kinda shootin in the dark but tried to get an idea to see if someone can help. Have hard starting as of recently....

Initial Key on(not cranking); pressure showd 52 PSI then dropped to 45-46 PSI after 1-2 seconds

I turned the key off and let it sit for 10 minutes and pressure dropped to 40PSI

Started car; pressure ran around 43-45 PSI at idle, jumped up to high-mid 50'* with throttle goosage.

I ran these test a few times to try and get it to crank hard, but the last couple times I tried reading idle pressure, the needle was fluctuating rapidly up and down 5psi. Needle stayed still when I started car the first few times. I tapped the gauge a few times but it kept doing it... could the jumpy needle be an indicator of something wearing?

Mostly Im just curious about the correct procedure/diagnosing for testing the fuel pressure on 2000-2003 SSEi'*.

Same basic procedure for both engines.
Fuel Pressure Test