While driving, my van has a loud squealing noise like a belt slipping.

What is your question?

The noise sounds like a belt slipping every time we start from a slowed or stopped position. It also makes the same noise just driving down the road - not constant, but every 2-3 minutes. It sounds like the noise comes from the drivers side under the hood. Our mechanic checked everything and nothing shows up as bad. It also does not make the check engine light come on. The transmission does change hard and jerky once in a while - not often. What could be the cause?

What makes this problem better or worse?

The farther we drive it, the louder the noise gets

How long has your 2008 Dodge Grand Caravan had this problem?

2 or 2 1/2 weeks