I've been torrenting for years and have had no problem with downloading and always share back to at least a 1:1 ratio.  I've noticed that when I download a file, and there are several seeds downloading the same file,  that I connect to them and upload.  My question is why is it that once my download is complete that I seem to disconnect from the group that I was uploading to ??  I leave the torrent seeding and will randomly connect to other users and finally give back the complete file,  usually twice as much.  I have ports open on my router,  I do not limit my upload speed but never come close to give back at my upload capacity.  I have 5 Mb upload but only manage to give back at a small fraction of that...usually only a few kilobytes,  maybe 5 or 4...sometimes more.  Occasionally I will give back at 60 or 70K.  I would like to be able to give back as much as I can as fast as I can.  I do believe I have setting optimized but would like others thoughts on the matter !!!

Your torrent upload speed is conditioned by several factors, not just the speed you contracted with your ISP. Leaving aside potential hardware or software issues (meaning, if you're sure your speeds aren't being limited by equipment or configuration inadequacies), the most common factors are:

- Being connectible, i.e. making sure your Tixati ports are properly forwarded and open in your router and firewall;
- The number of other seeds competing for the seeding of the same torrent;
- The usage of your upload (and download) bandwidth by other communications you're doing at the same time;
- Your distance to the final receiving target client, and the peering conditions between your ISP and the other involved ISPs (generally, the farthest away the worse);
- The download speed limitations of the target client;
- ISP interference with your P2P transfers i.e. capping.

You may want to take a look at Optimizing Tixati if you haven't done so yet, it could help.

Keep in mind that if this is something like "why can't I send faster to this or that guy in a different continent across the globe when just yesterday speed was fine to someone else in my own country ?", there isn't a lot else you can do. No miracles there.

Is it possible to set an upload limit while downloading and then uncap the upload seed when all uploads are complete?  In an effort to not throttle my connection, I have limited my upload speed.  I would like to set Tixati so that the limit is only in place while downloading.  When a download is complete, I would like to set my upload bandwidth to unlimited.

Yes it is possible, you'll need two bandwidth presets saved. Mark one of them as Seeding Default and the other one as Downloading Default. Tixati will automatically change profile when it starts downloading and when download finishes. These options are on Bandwidth View under Presets button.