How can you tell your starter is going bad on 1991 Toyota 4 runner?

Not sure if its the starter or the battery? Check the battery at a store. They can do a check on it for free. If its good then the starter could be bad. Bad starters don't work or they work intermittently. Usually just ehear a click and then when you retry it starts. That's the symptoms. Most places can also check the starter for you.