Hi there,

I don't fart around much in 7&9 series but the CPS is in my 200's. I can tell you what I think it is though.

Have you notice circular cut patterns in the asphalt in your lanes before you get to traffic lights.

These are coils of wire laid in those tiny trench like grooves.
They pass an electric current through them that creates a magnetic field but it's a very weak one in a since nothing is drawn to it.

The coil has a steady flux around the coil emitted evenly. When a massive object gets within the circular field the flux lines are disrupted from having an even flow. This reflection, if you will, is sensed as a "capacitive change" from the normal range due. It's called an "induction" sensed return. It could be reactance or impedance as either might be a better term.
I lose my butt in electronics. Just trying to sort two those out within different types of electric motors or circuits keep me second thinking what my mouth said!

There is a circuit monitor back at a signal box near by that trips timing counters and then relays to change the lights.

The CPS sensor works the same way in relation to holes drilled in the circumference of the flywheel.
In reality it's generated magnetic field is reacting to the absence of metal and then to the web of metal between the holes.

The ICU uses the information to fire plugs and sends signals too the ECU that modifies other goodies per a program. So both ICU and the ECU are always shaking hands with sensors and each other.

The CPS could be funky but that usually shows up as a random hard starting issue or it can straight out die to a no start. I carry a spare!

I suggest you square away the ignition components first. A bad rotor button can cause grief before it totally blows out. You do not mention if you are having a rainy or moist days that can bring out some very ugly symptoms.

Past the ignition you want to make sure that there are no air leaking cracks behind the Air Mass Meter sensor. No loose fitting clamps, ill fitting vacuum lines around leading to the intake manifold.
This includes the vacuum line coming from the cabin. There are lots of air bleeders in there.

You can temporarily plug the line to them to cross off them causing the randomness.
This car is not simple if it has any automatic climate controls.

When the car idles under a slight load the air flows are very slow. Any surge of excess air will quickly "bonk" on the delicate emissions mixtures and the computer will try do the "chase thing" to catch up! Computers are fast but it's only reactionary!

I hope me stepping around in this area I don't belong, gets you closer to finding the little Masked Gremlin!

Phil