Did you modify MMS.apk and fix what was causing it not to send properly? Is this a modified MMS from a Sprint rom? Or one from a Verizon roms like the rest of us have been using?
Would you mind sharing?
Also, are you capable of MMS while wifi is on by any chance?
Smart Phone History: Palm Treo650->HTC Faraday->Samsung Blackjack->Motorola Q->Nokia e61i->Apple iPhone 3G->HTC EVO->HTC EVO V->Moto X