Did you check inside the distributor cap to make sure all the contacts are in good shape?
It still sounds like a fuel problem to me, though. In my opinion, Techron is a good preventative maintenance treatment, but it won't work miracles on seriously varnished injectors. If you get through your half tank of gas and fresh fuel doesn't make it better, I would try testing the injectors for good flow and spray pattern. I'm not sure how to go about that on a CIS car, but it would basically mean pulling them one by one and having them squirt into a jar, while noting how they flow and mist the fuel. There is a good shop here in Washington that will clean and check injectors for a reasonable price ->
WitchHunter