I looked again at the 'check list' I posted. I think that a compression test is in order due to the fact that you still don't have any CEL popping up and you did look for vacuum leaks. Without any CEL, it'd be hard to know if the issue is due to a specific coil pack, or injector or what. That's my opinion anyways..
The only other thing that comes to mind is, you could always find a friend that has a good working MAF, put it in your car for a while and see how it behaves..