You are most correct! I would definitely agree with you. It may be the rack and pinion going bad. THis does happen from time to time. Especaily intermittently. THis would indicate a bad rack and pinion. However, also check the steering shaft from the steering wheel to the rack and pinion. sOmetimes these u joints stiffen up causing what seems to be hard or no power steering. This is also common on these vehicles. The U joints go bad in the shaft and causes this problem.
Check the lower joint and shaft assembly to see if the joint/knuckle is binding
Rack and pinion
Steering Column Knuckle
Power steering pump
Power steering belt slipping.