Took the car for a ride today and I heard a pop sound come from the engine some sort of backfire. When I got home I shut the car off and went to get the tools to adjust the fuel pressure regulator. Then I turned the car on and the fuel pressure with the vac line off and plugged was in the high 20s. Mind you, I set the FP to 43 weeks ago. I then realized I had the wrong size Allen key so I went and when I came back it was now 34, wrong key again came back now 39. It then stayed at 39 so I just left it there. All of these changes in pressure with me getting a different key was probably in 3 minute intervals. Any ideas why my fuel pressure is fluctuating like this? The whole fuel system is new new pump new injectors, tank, lines were cleaned, new regulator. Im pretty sure the car still has a vacuum leak but I don’t know if thatd be cause