The service manual explains how to use the white line marks of the belt to correctly align the cams and crankshaft. I believe that is where your problem is. You could be one tooth off in one, two, or all of them.
I have also done timing belt replacement in my Honda Accord and Acura MDX and the process is the same. I have all the service manuals of my cars to prevent mishaps.
Keep me posted on your progress, I would like to help you turn that van back into full operation. I love these vans.