Unusual weight

Hi Ya'llI was a big flightsimmer than took about 10months off, because i was busy in life, and my slower computer was always giving me a hard when trying to fly. I just recently started going through this forum again.i'm back with a faster computer and more time. (I did buy FS2004 hoping I would have this opportunity).Anyhow... I've been downloading freeware like crazy.I have been having trouble flying though with FS2004. Everytime i load a downloaded place. The fuel and payload menu says i'm overweight. i tried to ignore this by dropping the amount of fuel... but i was still having trouble managing to get M.80 on any place at FL310.Something just doesn't seem right. Are there downloadable fixes to help these problems?Thanks in advance for any help,Alp.s. i've been downloading airplanes that are for FS2004. (e.x. FS2004 original aircraft)