2004 Ford F-150 idle issue

I have a 2004 Ford F150 Lariat with a 5.4 24 valve engine & 4wd. It does not idle well at all & it will sometimes die at an idle & is getting worse. You can look under the hood at an idle & everything is really shaking. It is not missing when driven, so I don't think it is the plugs or wires, even though it probably does need new plugs. I had it scanned & it says it needs a mass air flow sensor. I know that sometimes scanning a vehicle can just mean throwing sensors at it & not fixing the problem. Does this sound like a mass air flow sensor issue & do you think now is a good time for new plugs, even though they will be a real pain to change, especially if they break. Thanks so much for your advice! Christy