iphone 3g bogging down!!

sorry if this has been addressed before, but i did not see it while doing a search of the forum.

for the last few months my iphone 3g has been really slow when opening programs and during keyboard input. I can type an entire word or more before the phone catches up to where i am.

I thought it might be 3rd party apps not fully closing, but i have done a full erase and restore and started the phone fresh, putting no apps beyond those that come pre loaded on the OS. The phone is still exhibiting the same issues.

The biggest issue is the inability for the phone to fluidly type.

Has anyone had this before and if so what's the fix? every time I've had a problem in the past restoring the phone to factory settings has worked!

Help!!

 

thanks for the advice, i'll try doing it in DFU mode. I don't know why but it didn't seem to help at all when i did a regular restore on the phone, even when i had no apps installed.