'02 Deville power steering

Just joined AF and hoping for some advice. My 02 Deville DHS' power steering goes back & forth from feather steering to Armstrong steering with no noises or any kind of warning. Pump? Power rack & Pinion?

When it goes away, does it come back with increased rpm? Does the pump or the gear leak? Without checking pump pressures, it's kind of a toss up. I've seen pumps and gears cause this on the DHS. Pump is way cheaper than a gear, so that may be the best place to start. Unless you can get the pressures checked at a shop that has the tools.

gmtech1, the darn thing seems to be totally arbitrary. I moved the car out of the way cause I borrowed a friend's car. Worked fine. Moved the car again an hour later - no power assist! RPM doesn't affect anything. It just works once, then next time not.