[GTP Dad]

I doubt that the autoparts stores can scan the car since it is an OBD 1 car so you will either need a code reader or to take the car to the shop to have it scanned.

The CPS would be my choice over the throttle position sensor given the issues you indicate. The CPS cannot be cleaned nor can the TPS either will need replaced. You didn't indicate the engine size so I can't tell you how hard it will be to replace without that.