Just double checked the Freightliner site, the following is a cut and paste.
For the front ride height on an Independent Front Suspension (IFS), measure from the center of the upper shock-absorber bolt to the center of the lower shock-absorber bolt. This dimension should be 17.5" +- 1/4".
Seem like the passenger side is right on, but the drivers side is high. On our rig, (Now keep in mind I've got the solid front axle) we only have one ride control valve in the front. Two valves are on the rear and the side to side control is done with the rear.
Maybe one of the guys with a Evolution chassis with IFS can jump in and confirm the number of height control valves on the front.
If yours is the same (with one only on the front) I'm betting you're just a touch high on the left rear. It wouldn't take much extra height on the left rear to push additional weight to the right front
Since the chassis is rigid when one wheel is slightly higher, it's like the chair with one leg a touch longer. You end up with a rocking chair since the longer leg and the opposite corner leg support more weight than the other two legs. If your left rear is to high, the right front is carrying more weight than it should.
If you can drop the height on the left rear, even only an 1/8" or so, you might find the right front comes up to it's correct 18"
FYI The rear suspension should be 9-3/4" plus/minus 1/8"
Here's some more leisure reading for ya
Freightliner Recreational Vehicle Chassis Manual
Freightliner's "Knowing Your Chassis"
Joe & Shelly, Justin, Tyler, Alyssa | Butler PA
2008 Tiffin Allegro Bus 43QRP|Cummins 425|Honda CRV