MAF problem

[Nate29]

Ok im having a maf problem with my red top sr.I come to this conclusion cus it won't go past 3k when driving but it will when in netural.not throwing a code 4 it but i tested it and the power wire is reading 12v and the signal wire is reading 1v and what iv read its spose to be 5v.but iv switched out mafs with a buddys and it still was doing the same thing.So my question is is it bad wiring somewhere down the line or is maf bad.thanks for any help.