Okay, so as so many of us have posted, the focus has a tendency to develop an annoying squeak/creak when going over bumps. It comes from the rear, and can be on the left or right.
I could not believe people when they said that it could be the e-brake cables, but I secured them anyways. They go through a loop that is bolted to the frame. That bolt can get loose too, and cause its own squeak. The loops are on the sides of the car, about one foot from the rear wheel wells. The big cable goes right through them, so you can't miss em.
BUT, for me, the noise still came from time to time. So, I went under there and really looked all over. Turned out there is a plastic clamp that runs under the rear seat. It gets loose over time, and when you hit a bump, it can move, causing that squeak. It holds the e-brake cable in place further up the car, away from those bigger loops that are about a foot fwd of the rear wheel wells. This clamp is about two feet in from the side of the car, more near the center.
Trust me, when you touch this spot, and you hear the noise, you know IMMEDIATELY that this is what has been driving you nuts. It makes the exact noise I hear in the car. It sits up a bit, recessed under the back seat. I tried to get some pics of the spot for you guys. I put some grease on it, but it also flips over (rotates), and you can then put the cable back into the clamp. When flipped, it tightens right up. No more noise. I dreaded when I first started to go over the usual bumps that cause the problem noise, but boom, no more noise.
The white clamp in the middle is the problem, with the green thing going through it. Its all tight now, in that pic...before, the clamp faced upwards instead of down, and it was loose.
You can see some of the white lithium grease I applied squishing out from under the clamp.
Look for those other hoses/lines you see in the pics, and you will see it.
If you have this damn random rear squeak, check this out. If you try it, post up your results!
Hope this helps. I know it drove me NUTS.