I am having the same exact issue. I have tried flashing OMJ's Alltel ROMS (Both versions) and I cannot get MMS to receive. Sending works fine on a few different server configurations (gateway: mms.alltel.com or nothing both work (send), Server: mms-mt.alltel.net/servlets/mms and mms.alltel.net/servlets/mms both work (send), port 8080, WAP 2.0). I have tried deleting IOTA, but all this seems to do is suppress the Sprint Vision provisioning error notifications. I have deleted the IOTA registry settings and modified the ArcSoft registry settings to no avail.
I have also tried all of these things after installing Lenny's ArcSoft Alltel CAB with the same disappointing results.
I have tried both letting customizations run and bypassing.
The only solution I can think of would be for someone to create a custom ROM with every trace of the Sprint IOTA settings and all traces of the Sprint ArcSoft version removed, so the Alltel customizations and ArcSoft version can be installed cleanly. I do not feel I am up to doing this myself, as I honestly dont know what I am doing with ROM kitchens.
Anybody out there up to this challenge? Is it even possible to do? Many of us Alltel customers would be eternally grateful!!