Rear air bags not dumping fully indicates a stuck exhaust valve, check valve issue, or height control valve problem. Listen for air exhausting when dump is activated. Check for obvious blockages and try manually releasing air via Schrader valves on bags.
Front air bags not filling with air exhausting from height valve means the valve thinks chassis is too high. Check linkage connection and adjustment, or replace the stuck height control valve.
Your symptoms point to a leak in the rear air bag system or cross-plumbing between tanks. The gurgling sound and faster rear sag indicate air transferring from front to rear tank through a compromised component.
The electrical manual for your 2007 Dyna Max IE250's Dyna Air Ride suspension is typically found through Monaco Coach Group archives or specialty RV parts dealers, as this was a premium system installed on select Dyna models.