01 T&C Suspension/Alignment issues

I hope someone can help. 01 limited, 3.8, 78,000 miles on it. I took it to 6 shops to do the alignments, no one can seem to center the wheel, it's always to the left or right alittle. They all tell me that is fine. I don't like it so I tried it myself. It seems that the front wheel base is shorter than the back. The back is wider about by an inch. Tried the string thing but can't get it right. Anyways I have been making small adjustments on the tie rods. I have the Hydroedge tires on them and use the two center grooves to pull measurments from, then based on that and how it was pulling or wheel position I make the adjustments. I have the steering wheel centered, and the first time I got to this point the van drove beautiful, 459 miles on a full tank, was getting 32/33 instant mpg at 45 mph, 30 at 55 mph. I could let go of the wheel and it went straight. It went over bumps smooth too, manholes too, not big ones.

I have about 34 psi in the tires cause these Hydroedge tires ride like concrete being they are 80,000 mile tires.

I was told the shocks and struts are fine. Dealer replaced sway bar bushings, sway bar end links in front are new, sway bar end links for rear are new. Dealer says subframe is good and straight. Rack and pinion is new. Outer tie rods on both sides are new too. Brakes are new and no dragging. Calipers are not sticking, they are well greased.

I have a slight shake in the wheel, I think that is the tires doing that because they are one direction tires and when the belts shift somewhat your stuck with it.

Anyways, heres the problem, when I get it perfect it does good for alittle bit until I go over a hump like coming out of a parking lot that shakes the van side to side. Then it seems to want to go right so now I have to turn the wheel more to the left to stay straight, and when it drives like this it feels like the rear end suspension is going to come off when I hit a bump in the road. And all those slight humps in the road puts the van all over the place. All the stuff hanging from the mirror go left to right too, normally they dont. I see cars back off when this happens, to me it looks like the back end is going from left to right over humps, I think it's the front doing it and the back is just reacting. I have to take all those measurments again and sure enough I have to make more adjustments. Some how the toe is out again, normally the front tires are facing in again. Rack is tight too. Example, down the road I have to drive over 5 manhole covers, nothing big, when all is driving straight I barely feel them. Then after a big hump that shakes the van coming out of driveway or on the road, it drives like crap, it feels like the suspension is going to fall off over them. The back snaps back sometimes too. I hope this makes sense. Please anything ideas would be great. I have also be told everything is tight suspension wise. Somethings just not holding in place it seems. Could I have control arm issues?

The rear axle has a bar that attaches to it and the frame, don't know what that is, it's about 3 feet long, it's not the sway bar. And I think the suspension set-up on these are the same as earlier ones, starting at 96?

Maybe this will help more, It feels like I'm driving around with 10 psi in all the tires but with pressure.