1996 Toyota Camry posible ground, starter, relay?

Did you mean that the starter is still running after you disengaged in the key ignition (start) position.

Before you changed the starter, is it the same problem. If yes, Then it is not the starter. If no, the starter with magnetic switch assembly is defective.

Possible causes:
1. Your starter relay located beside the air cleaner is defective. Start with the starter relay.

2. Your ignition key switch assembly is defective

3. Lastly, it is the starter. Either magnetic swith assembly of the starter is defective or starter gear is not disengaging.