Steering wheel not centered on my 96 chev caprice classic

You will need to have an alignment performed to center the steering wheel. If any front end steering parts have been changed, the steering angles will be affected causing the sterring wheel to be off center. Also, hitting curbs/potholes can affect the alignment off setting the steering wheel

http://www.gmpartsgiant.com/parts/gm-switch-as-17990636.html
Been there done that.
It is the switches in the steering wheel.
Remove the battery cables, then pull the air bag and replace.
Took me months to find this place, see above.

Most common low on freon,or the low pressure cycling switch,If its beacuse its low you should fix the leak and refill.

Near base of steering column..

You have to remove your steering wheel and the with the assistance of a special tool you remove the plate under the steering wheel. Then you remove the screw that holds the ignition switch it will come out.

After you install the gear box you need to adjust the free play in it. There should be an adjustment screw on top of the box. The screw will have a loch nut on it, loosen the lock nut and turn screw to adjust.

Replace the steering box - check junkyard for one of similar model/year or ask Pep Boys to help by cross ref. your make/yr with others. Pep Boys will even install for you.

low power steering fluid
worn out steering box
bad power steering pump

door pins may be bad, you doors may also be sagging at the hinges causing a bad connection, your lights will dim when you brake because of a draw on the battery, but it sounds like your pin switches are bad