I'd be chasing that vacuum level first...
Idle air bypass motor sounds like it's stuck open to me. (couple "love taps" might get it unstuck)
No trouble light codes coming up?
www.fordfuelinjection.com has lots of valuable info on this system. Basiclly the Mass-flo is a stock '93 Mustang setup with a GM LS 6 air meter adapted to it.
Could be a bad TFI module, but it doesn't sound like it. Might try clamping off the PCV hose as well.