The Haynes guide has detailed instructions for voltage testing both the CPS and the MAF.
Think of the Cam Shaft Position Sensor as the computer controlled car's equivalent of the good ol' Distributor. But instead of a bunch of spark plug wires coming out of the top of a big plastic cap with a contact pick-up disk spinning around underneath, today we have a little sensor spinning around at the top of the shaft and it sends a short electrical signal to the PCM (the "computer") every time cylinder #1 passes Top Dead Center (TDC). Then it's up to the computer to make sure the spark plugs each fire at the right time.
In your case, the little sensor on the top could be on its last leg and sending a crappy single to the computer, which then tries its best to do the right thing, but not good enough to go unnoticed by you. Or the sensor could be fine, but the wire from it to the PCM could be shorting out somewhere. | 
