Phantom rev limiter?

2012 Peterbilt 386 with an ISX.

Randomly my truck in 10th gear will not rev above 1570rpm. The pedal goes dead, boost drops off and the truck will not accelerate any more. Normally it will spin to 1640rpm in top gear. While I don't drive fast enough to hit that limiter, there are times when Im passing someone and need the extra rpm to pass them quickly. This problem can last for days/weeks/months then go away.

Im going to inspect the speed sensor on the transmission to start, but can a camshaft position/speed sensor cause this? I am getting a random stored code for the CPS, but the truck always starts and runs perfect. Not even a hiccup.