It might help to add some detail about what this means. Are you saying that the starter does not spin the engine? It's just click, click, click, then spinning happens? Also, watch your gauges and the ammeter. If they all go dead, then come back to life that's a sign of a bad battery cable connection. The heat from the starter motor draw causes the bad connection to expand and open. Then it cools and closes. The small spade connection at the starter solenoid can be loose also. Same effect. I almost replaced a starter once, but instead just repinched that connector. It was loose.