45 psi under what conditions?
It should be 45 PSI with 5 psi of vacuum which is half the vacuum your car should produce at idle.
Check fuel pressure with the vacuum connector off, it should be ~50.8 psi.
If unplugging the maf is generally what we consider "the maf test" which implies the MAF is bad. I agree its not an absolute, but its probable that it is at fault.
I'd suggest hitting up a junk yard and picking up a few MAFs and trying those out. Or cleaning the one you have. Better yet, warranty it.
