2002 Dodge Caravan Sliipping occasionally - Different Opini

I have gotten several different opinions from several sources, a transmission shop (highly recommended), the Dodge Dealership, and Ammco. The transmission shop first, after driving it and noticing the seemingly double rotation of the rear tires on occasion (not often), recommended a tear down of the transmission and then a rebuilt transmission if it turned out to be needed. He also said my spark plug wires were "shot" and he would replace them for free. His break down charge is $485. Then he said there was noticable arching when the car was up on the lift and it may only need new wires, plugs and a reconfiguration of the computer to the transmission.
Teh Dodge dealer said he's never heard of such a thing, Ammco in all their brilliance said there was nothing wrong and they couldn't tell if it was slipping or not. They apparently drove it around the block and it didn't react the way I said.
None of the computer checks showed anything at all and the engine is running fine.
I'm disabled and my husband is a teacher and we don't have the kind of money to waste if there isn't anything wrong.
The systom occurs usually after leaving a stop sign, etc and after pushing on the gas after a minute or so it does this thing where it feels like the rear tires are double or triple rotating. I call it slipping, but there is another name for it I forget what he said.
Because it's an accessible van(wheelchair hydralic ramp), fortunately none of the VMI accessiblity gear on it has anything to do with it.
Does anything make any sense or can you all give me some advice?
Sorry, after paying for all these estimates, I can only donate a small amount.

Kathie Kelly