P0171 & MAF

[Caveman]

I have a 97 Maxima GLE. Mechanic replaced plugs, PCV and knock sensor (had to remove manifold to do this as he physically could not contort enough). Replaced manifold gasket and triple checked all hoses, pipes and connections. All OK, no leaks found anywhere and everything where it should be. He also had to replace one of the injectors since two of the four little prongs were "missing" somewhere?!?

Shortly after (maybe a week or so), car started idling roughly, and when engine cold will barely run until warmed up. Once on the road and running, seems to run fine. Engine light came on and coded P0171 (Fuel Injection System Lean - right bank). After some fiddling about and checking MAF voltages (seem to be OK per Haynes manual), disconnected the connections to the MAF and the engine idles smooth as new. Of course it won't run an inch with the MAF disconnected.

Is my diagnosis correct that the MAF is finished and a replacement is needed? I am having enough trouble trying to find a used one and don't want to spend big $ on a new one. A refurb one is almost $200. Worried that I get the part and this doesn't solve the problem. Any thoughts or guidance would be appreciated. Thanks.