New FASS installed, engine vibrates
 

Hello thanks to everyone for the help on my last post, turned out the VP was shot so now she has a non-reman bosch unit in there. Had a FASS Titanium 150 installed a month ago, drove it home from the shop reading a steady 17psi but the motor had a vibration at all rpm's. Started the next day, pressure was waving across an 8psi range and then holding unsteady at 17 or 11 psi back and forth, and has been flickering at 11 ever since. Only drove three times after the install, pressure is still reading erratic although the fass sounds perfectly smooth and steady and the engine still runs with a vibration same as it did with the bad VP only now its worse and the VP is new. The return line ball and spring are good, only thing I can think of is the mechanic couldn't get it to fire for 20 mins until we found a low PSI shutoff switch in the line then about a minute of idling later he revved it high checking the pressure. Blowby hasn't changed at all, no loss in power response or starting ability. Have not been able to locate a fuel leak in the system either. Any thoughts?