Bicycle Mechanics - front derailleur question

I have a felt f90 which comes with a sora front and tiagra back derailleur and is a triple. I would like to wipe the whole thing and move to 105, but unfortunately money prohibits that right now. OVerall the bike rides great EXCEPT for the sora. Would it be possible to buy an older 8 spd 105 or ultegra front derailleur to replace the front sora? I am not sure if there would be any issues w/ compatibility. Thanks.

As many people here will tell you, there is nothing particularly wrong with a Sora front derailleur.

Are you sure yours is properly adjusted (angle, height, limit screws, cable tension, lubrication)?

http://www.parktool.com/repair_help/howfix_frontderailleur.shtml
http://sheldonbrown.com/derailer-adjustment.html

I would never stand in the way of somebody who wants new parts, but you should upgrade for the right reasons ;)

It should work fine. You will likely not notice any performance difference, since the precision you are looking for is in the shifters, not the derailleurs.

The Park Tool link that neil0502 provided is a good one. Spend some time adjusting the derailleur properly - start right from the beginning, detaching the cable and all. Sora will shift very nicely, especially with a Tiagra RD (the Sora RD is the only truly crappy part of the group).

I'm all for getting new stuff, but in this case I don't think you need it. Poorly adjusted Ultegra will shift just as badly as poorly adjusted Sora. :D

One issue I had when I went up to the 105 from the sora on the front derailleur was the cage area seemed to be a little narrower. I widened that by putting a small nut where the one screw is on the cage. It opens it a little(about 2 or 3 mm), so you don't have quite as much chain rub. On the rear, I went to a Deore, just because my largest cog is a 34 tooth cog.

coooooooooooool. I am glad to hear I don't need to buy a new part, I'd prefer not to spend the dough. I knew about sheldon brown and thought I had adjusted everything correctly, but perhaps I'll do it again. Thanks for the help.