You have a loose belt or it is glazed. The reason why it quites down after a while is because the belt heats up, and cause better grip on the pulley. Solution: replace belt and tighten properly. If the problem persist, then it is the the idler bearing that is going bad. If it is equiped with that.
My Altima 1999 has a thumping/knocking sound as it moves. Its louder on slow speed from 20 to 30mph....
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My Altima 1999 has a thumping/knocking sound as it moves. Its louder on slow speed from 20 to 30mph. I just replaced the worn driver side wheel axle with a new one hoping that would resolved it but it didnt