I'm throwing a p0101 code for MAF.There is three wires a red which is 13volts and power I assume a black which is ground and a white which tests at 4.4 volts and I assume is the signal wire .when I accelerated the 4.4 signal wire slowly dropped to 4.1. I was revving really high just to get it to drop to 4.1. Usually when I test mass air flows as I bring up the engine the number increases not decreases. I have four different mass air flows all from the junkyard and everyone I tested did the same exact thing. I'm wondering if they're all bad or if there's something I'm missing here. If anyone can help I would really appreciate it. Am I testing a correctly I'm on voltage DC. I tested for the ground using ohms that's how I came up with the black wire as ground. Can someone tell me what I'm supposed to be coming up with for numbers.