Check Engine Light with Code 214.

[Indispensable Explorer]

When I started my Explorer this afternoon(4.0 OHV with 300k) I saw the dreaded Check Engine light. The light came on about a year ago but went off before I could check the engine. I popped the hood and used a paper clip to check the codes, 633(Vehicle must be in 2x4 high or 4x4 high. My gem module is malfunctioning and it flashes the 4x4 lights.), 452(VSS malfunction, which a mechanic "fixed"), and the code of concern, 214(error in cylinder ID(CID) circuit signal - Ignition systems). I have not done a dynamic test with the engine on yet.
I decided to take another car so I wouldn't risk damaging something, but what would be some common fixes to this code? Would I damage anything by driving the vehicle with these codes?
The engine is long overdue for new plugs and wires(they are over 200k old), could this contribute to the problem? I've been doing a little reading on the forum and found that it could be caused by the Cam Position Sensor, Crank Sensor, or Ignition Control Module. How should I go about testing these systems?
Thanks,

 

[Indispensable Explorer]

A quick update, I had to go somewhere this morning so I rolled the dice and drove it. Driving back home the check engine light turned back off, and it did not come back on through the remainder of the drive(about five minutes). I do not expect the check engine light to stay off so I am still planning to test these systems, but I do not know where to find the Cam Position Sensor, Crankshaft Sensor, or the Ignition Control Module. Any help finding these parts is appreciated.

Also I was wondering how long codes run in the system, I had a shop fix the busted VSS gears while they were rebuilding my transmission and then the code shows up in my test. So I am concerned of how much they actually did. The vehicle shifts like it knows what speed it is going and the speedometer works again so maybe they did not clear the codes?

Thanks,