2003 Manual Saturn Vue?

I have a 2003 Saturn Vue with 115000 miles on it, and last Saturday as I was leaving the Mall the steering wheel was very hard to turn especially to the left, then my Service Light went on then the Check Engine Light, I drove over to Sears and checked my oil and it was low, put some in and about 20 mins later the steering was fine. Drove the car to work Sunday night and no problems. Took the car to the mechanic on Monday cause the service light kept going on on my way home from work, but the steering was fine. Today the steering did tighten up again and the service lite stayed on. I also noticed that the RPM's when Im at a stop light stayed at 2 for a few seconds then dropped down to the 1 where it should be when your stopped and idel. But my concern is the steering wheel being hard to turn the mechanic checked the computer in the car and nothing came up just that the car stalled with the key in the ignition which is true teaching my nephew how to drive. I checked the oil today when I got to work and its fine I use Amsoil. Any answers????