2007 9900 Eagle rough ride

Hello, recently purchased a 07 9900, it is 260ish wheelbase with 12k front and has a Hendrickson HAS rear suspension. It rides severely rough over expansion joints/sharp bumps on the road.

Replaced height valve, set height to Hendrickson spec, replaced shocks, set cab ride height to 6.5”, checked that cab does move up an down freely, slid 5th wheel forward/back. No changes.

Is this HAS suspension just rough riding junk?

Another thing to note is the truck slopes nose down quite hard, the rear rear axle will have the bags out of their saddle while the front rear axle bags will still be in their saddles due to the frame sloping towards the steer. Front springs look OK and front shackles are only a little leaning rearward. I am thinking of replacing the steer leafs, remeasuring frame slope then adjusting leaf spring blocks until frames levels out in hope to fix the ride. Is there anything else we could be missing? Any input is appreciated..

 

Tires are all China brand with about 30% remaining, set @ 90lb..not the best that’s for sure. Been saving to purchase some XDN2’s because they have been awesome on our other truck.

 

Still fighting with this, did new leafs and leveled out the truck with spacer blocks in the front. Slight improvement, but nothing great.

Another thing we noticed is the cab air ride hits the bump stop often, the height is set proper at 6.5" and no noise of leaks. Could a bad leveling valve cause it to bottom out or is it normal?