After nearly a year I managed to get level 3 tech to file his own ticket based on all the data he saw and client relations allowed to send in 3 plant tech trucks at the time when my problem(which is basically what yours is) occured the most. They went from node towards end of line in my direction pole by pole trying to catch what was causing upstream snr to keep dropping between 26 and 18 back and forth and it would not always show up. After 3 hours they found a street and tap that when unhooked all upstream snr went up to 29+ and no jumps, they finally determined there was illegal cable hooked from that tap to some device that must of been causing the problem. Once they called in main office and disconnected that tap ever since that upstream problem went away. Situation is similar to yours although when my problem occured the upstream speed would be bad and packet loss but downstream was not as affected as yours is so its possible it maybe similar issue or combination of things going on. good luck.
Damn nearly a year, that's horrendous . It does sound like my problem though. Many times my upload won't even connect to the speed test so its definitely one of the issues.Thanks for the info. I'll ask about upstream signal to noise ratio if I ever get in contact with them again. Lvl 3 won't even talk to me right now, they are trying to send another local tech for the "local issue". Hopefully upstream snr is the magic word.