Shocks and front tire air pressure would be the possible causes .
The air bags ; old or new ; will always inflate to the same pressure .
Do you have your loaded for travel front axle weight ?
Is that weight less than the FAWR ?
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.