All, tow a 6.5K boat with the 2007 Yukon Denali. Love it for the auto level feature however last year the system would not hold air. GM dealer diagnosed airbags as needed replacement. Ordered a pair from Arnott, all good for rest of year. Pick up boat this spring and same issue, riding low, compressor running but not holding air. Occasionally after compressor runs (with or without trailer load) I hear an air rushing sound which stops instantly like (the air dryer?). Anyways, Arnott says no way their shocks already failed, said they are beefier than stock. What else can I do to diagnose? No codes on dash BTW.