Sound like your Caravan is just now getting broken in well. Two of our friends have each had 2 Caravans in the past 20 years. All 4 of them got well over 200,000 miles with hardly a problem. These things must be pretty well built.
I purchased a 2004 Dodge Caravan 6 cyl new, from my local Dodge dealership. It has a very loud knocking sound and it loses power when it knocks. Usually once the engine is warm the knocking begins. It has been back to the dealership many many times with the same problem. All I have been able to achieve is a band aid solution to this problem. My Caravan began with this problem at only 4,000 miles, and it only has 24,400 miles now (5 years later) and the problem is still there. The van is still under warranty, however, I have lost faith in the Chrysler/Dodge service departments to correct it. I will have to pay and get it fixed through a private shop. Very disappointed with Product and Service.
To 21:55: I'm very sorry to hear of your problem. We have encountered total lack of concern for customers from Chrysler in the past. The Dodge dealership my brother and I bought our new Dodges from in 1988 flatly refused to fix ANYTHING on the cars in the first MONTH. We were told "We won't fix it and you can't make us". My brother appealed to Chrysler's arbitration board and was totally ignored. He was told "We'll fix it but you have to pay for it". This was on a car less than 6 months old. He gave up and traded for a GM vehicle. He never bought another Chrysler ever. I paid a private garage to fix mine and put over 100,000 miles on it. It was a VERY good car. In spite of the reliability of the car, it was 14 years before I even looked at another Chrysler product. They are the one U.S. auto maker I have little regret about watching go under. I'm sure that their current "lifetime" warranty is just as worthless as their infamous "7-70" warranty which they would not honor in the FIRST WEEK of ownership.
With all that said, Chrysler's vehicles have always been VERY reliable for us. My family put over 240,000 miles on one with virtually NOTHING beyond routine maintenance. Our best friends have put nearly a quarter of a million miles each on two Caravans and currently own a Chrysler Town and Country. It, too, has proven flawless.
You might want to consider contacting your local Better Business Bureau or an attorney. You definitely have a problem and you are definitely being ignored just as we were. Make yourself heard. One of our neighbors was so disgusted with his Toyota Corolla (the engine seized at 30,000 miles) that he rented a big truck and hauled it all over the area with signs stating that Toyota wouldn't fix it. A photo was printed in the local paper with the headline "Oh what a feeling to DRAG a Toyota". I heard later that they finally DID fix his car. Hopefully you won't have to resort to such extremes!!