i want to know if there is a kit or a trick to lowering the leaf springs in the back or maybe is there a air bag kit made for this van :banghead:

Couple ways I can think of. Used to be you could flip the rearend on top of the springs, but the shape/configuration of the axle doesn't allow that easily.
You could get some of those leaf spring boosters that look like a bar with clamps on either end and instead of jacking it up and installing them-load it up so it's down and install them nice and tight.
All they do is keep the spring arch where it is when you install them.
Makes sense it should work the other way.