Our Chevy Metro won't start unless it is jump-started. on 2000 Chevrolet Metro

We had the battery checked and it is good, even bought a new battery and tried that. While the engine was running, we have removed both battery cables and the engine continues to run. If we turn off the engine, it will not crank unless jump-started again. What else can I check?

Asked by for the 2000 Chevrolet Metro

Possible starter.
I would have the voltage checked going to the starter wire.
Not the big positive wire on the starter,but the small wire.

When you jump it your adding more amperage to the starter.

Could also be corrosion on the cable and wire at the starter it self.
Thanks for the input. We will check that out.