Faulty Ignition Switch?

My 1999 DeVille will suddenly cut off all electrical power. Radio, clock, trip computer loses memory. When go to start, none of the dash lights, door locks, etc. Will come on. Then if we turn the key back & forth, turn or tilt the stering wheel enough times the power comes back on.

Beleive it is a short in the stering column or ignition switch. When shopping for parts, there are 3 different ignition parts listed. Any idea which part to try first? Is this hard to fix? :)

If I replace the key switch itself, will this affect the anti-theft device?

Thanks in advance.