Low Vacuum at Idle

[95_240sx]

OK guys, some of you know and some of you dont, but I have been having some major issues with my car and the headgasket/stock headbolts/arp head studs/o-ringed block problems and i finally have them sorted out. After fixing an initial problem of somhow the cam timing being a tooth off, at which point I was making about 300ish mmhg (about 13in) of vacuum, to having the correct timing and making about 425 mmhg (about 16in) of vacuum which is more correct. For some reason now the car is making about 115mmhg (about 4.5in) of vacuum. Hmm...any reason behind this? I havent looked into it too deeply but I might need some ideas of what to look for.

ThanksRick