1991 Chevy Cavalier ignition key or ignition switch?

My car has been acting funny lately, i was wondering if you can help me? So i go to start my car and it starts fine and drives ok, but heres the problem. Suddenly everything stops working, my radio shuts off, the windshield wipers stop, heater stop and so on,but the car remains on while im driving. but when i turn the key and hold it for a second and let go everything comes back on and work, but it shuts off again after a while. So i guess my question is would the problem be in the "ignition switch" or the the "ignition key lock"? i feel like its loose but i dont know and i dont want to spend money on the wrong part. if you can please help me for this is really frustrating without my heater and radio its boring to drive.
Thank you .. have a nice day