Fuel pressure issue

Hello.I have mounted a very freeflow fuelfilter and when I fired up the pressure hold a steady 6.4psi.I took it for a spin and all of a suddent pressure is only 4.3psi,drove it for a while and gave full throttle,it went back to 6.4psi.The pressure continued to act like this all the time.
Could the needles in the carb be stucking and leaking?
Or what could it be?
Thank´s Gresse

Your carb needles will not cause your problem, if they stick closed, you lean out, if they stick open , you flood out. Your problem most likely lies with you fuel pump (electric or mech.)? you could also have a restriction in you line or your pump may be pulling in some air.

Pressure is a measure of resistance. When you use from fuel the needles open and PSI will drop a certain amount depending on fuel usage. Returning to the 6.4 PSI tells you the fuel usage slowed and the needles closer up creating more resistance upping the PSI.

Thank´s.It´s a Holley 110gph mech.
I pulled out my needle today and found metal shavings in it.The threads in the floatbowl was gone.I have to buy a new bowl and needle and do some more testing.
Thank´s Gresse