1998 GMC Jimmy Ignition switch or wheel shaft?

My car has gone through a lot of repairs and tuneups recently, including having several fuses replaced - but something new has started happening. Sometimes when I start the car the gages won't light up, and it won't show the mileage, fuel in the gas tank, etc. -- But it will light up the "Service Engine Soon" warning. When this happens, the ignition switch also sometimes locks into place so that I can't remove or turn the key, until I jostle the wheel a bit. The car will still start fine, and will also drive - although I've noticed it's very, very sluggish to accelerate when this happens. Typically the gages go back to normal after a few minutes of driving. And I have also found that if I deliver a swift bump to the steering wheel, the gages work properly again. This happens once every couple weeks, sometimes more.
I know pretty much nothing about cars - but IF it is just a faulty ignition switch, are those easy to replace? (I'm really broke, and would like to do it myself.) Or does it sound like it might be something different?

**Today the gages have been going in and out whenever I hit a bump on the road. Other than the engine feeling sluggish, maybe this is something I don't need to repair (. She asks hopefully.)