Try updating tekkit server software to 3.1.3 and make sure you are not puting all your ram into the server and make sure you have around 3gb ram for yourself.
I don't recommend adding mods tobase tekkit but here's a few mods:
http://www.minecraftforum.net/topic/871749-keep-inventory-on-death-mod/
http://www.minecraftforum.net/topic/1461240-132-keep-items-on-death-smp-and-forge-compatible/
I wouldn't recommend back dating but go to your .techniclauncher folder (It's located where your .minecraft folder is) and delete the tekkit folder, Start up the launcher select the version you want and try to play.
Add more ram (1GB for you and a friend or two, 2GB for a small server, and 3GB for a normal server). If that doesn't work redownload Tekkit server software and try again.