i recently removed my plenum, runners, fuel rail, and injectors so i could port the TPI intake. while the injectors were out i replaced the orings. i assembled everything and started it up and it ran fine... no audible or visible leaks (fuel or vaccum). however, now when i test my FP, the needle vibrates back and forth, not giving me an accurate reading. my dragstrip performance has also suffered a bit (lost about a tenth and almost 2 mph). before the TPI work, this never happened, and the FP guage needle was always dead on with no movement. what do you think has caused this?

 

If it is shakey with the vac line on, but still with it off, then you probobly do have some vacuum leaks. If is shakes with the vac line off also, then you could have some fuel delivery problems/leaks.
Mine would shake either way, cause my pump was pumping just barely enough fuel to maintain the pressure.
But since you didn't have that prob before I doubt it has anything to do with your fuel volume.