iPhone 3g: baseband 05.13.04, bootloader 5.9, model MB048, firmware 4.0

ok, i updated my iphone to iOS4.0, then jailbroke (redsnow) it for the first time. i played with it for a few days and realized there are not alot of apps in cydia that work with iOS4.0 and it made my phone lag and run slow. it also did not have MMS like iOS2.2.1 . so i restored it with itunes. but my carrier still says "iPhone" like it did when i changed it with makeitmine. and i still dont have MMS. i cant change my homescreen background but i dont know if thats normal for a 3g like i cant multitask. i tryed downgrading back to 3.1.2 but my itunes keeps having error 1015 and i cant find a copy of quickpawn that works on my computer.

any ideas?