iPhone 3gs lags and freezes up constantly...

I have a 3gs that constantly freezes up when im using data, using apps and it's also saying i have no service in areas that i normally have full bars. I'm just wondering if I restore my iPhone as a new one, will this help the problem. I've tried restoring form a backup, that hasn't worked.. Just wanted to check before i do this, so i don't end up losing everything and it dose not solve my problem.