Now before anyone says do your research, i can tell you that i have. I have an 06 RX 8 with just over 100k miles. My power steering went out about a year ago. My indicator light came on and obviously the car became very difficult to drive. However for a few months the power steering would temporarily fix itself for a few minutes after i filled the gas tank to full. That eventually went away. I have checked the connectors under the air box multiple times as well as cleaned them and even went as far as to splice them together. Ive checked the battery terminals and the fuses. I followed and checked all connections on the harness to make sure there was not a fault somewhere in the wires. I've done the hard reset by leaving the positive connection on the battery disconnected and the manual steering reset. I recently went on a work trip for 6 months and made sure to leave the battery disconnected. I come home and reconnect everything and give her a start. Obviously after being out of commission for an extended period of time it took a little bit to get her to start. The power steering got worse. Previously i was able to turn the steering wheel with some effort while she was on the ground. However now it feels as if the entire steering column is seized. At this point im not really sure what to do. I took her in for a diagnostics and they pointed to my rack and pinion and steering gear. Had both of them replaced and she drove great for about 1-2 months just for the steering to go out again. I'm at my wits end at this point just trying to figure out what's wrong.

 

So the steering is a purely mechanical rack with electrical assistance. Meaning you can literally disconnect the electrical and be fine. (this does cause extra stress on the steering knuckle joint, mine failed after a year of no power steering.)

Electronics wise:

• The Power steering unit under the ECU has corrosion issues and can die internally. However this should be your last ditch effort along with replacing the rack.
• The Torque sensor wires are extremely small and finicky. Simply checking continuity at a stand still may not account for bouncing/shaking. Typically the second main source of failure is due to the coolant overflow tube draining right on top of the connector on the fan shroud. I just cut and hard wired this connection since it really isn't needed. Go buy a simple crimp kit on amazon and a 3:1 adhesive shrink wrap kit.
• Grounds are just as important. There should be a ground on the rack itself which can get corroded and also one to the chassis which can corrode. Clean up the surfaces and put conductive grease over them.
  
  
• Next comes the software side of things, completely disconnect the battery and let everything reset for an hour(do this while working on the above). Put the key in the on position and turn the steering wheel all the way to the left and then to the right. One of the power steering or traction control lights should shut off once done. Turn the key off and then start the car. This reset essentially figures out the extreme left and right in order to re-homes the center positioning for the control module. So lets say a ground connection breaks and it doesn't register a turn. Now your home will be off to one side. Which will feel like the steering wheel is really easy to turn one direction and not the other. Once the center is off to one side, the power steering will shut off if it detects itself going beyond your previous extreme left and right values....... So sometimes if the ground were to break there is a chance you don't take too many big turns to ever hit beyond an extreme for quite a while.

In your case it sounds like it is a wiring issue, potentially people working on it got the wiring happy and you just so happened to not turn excessively like I said above.

 

What did you use to splice the connectors together?

Ive used crimp connectors since my power steering was finnicky just like yours. Never had an issue since (its been about 6+ months).