As the name suggests, Seafoam was created for water/moisture related problems effecting boat engines in the 1930's. 50% Pale oil (lube), 30% Naphtha (mild solvent), 20% IPA (fuel stabilizer). Over the years its been marketed and used for many other purposes. To debug a potential fouling/misfire issue on a modern engine running E10 unleaded, recommend a modern fuel system cleaner containing the powerful cleaning additive PEA (polyetheramine). Very few fuel system cleaners contain PEA. 2 readily available at walmart are Techron Concentrate Plus and Gumout All-in-one. You've stated "techron" for one tank. There are 2 techron products with varying strength. If it was techron conentrate plus, you've already tried the one of the best available fuel system cleaners. Maybe another shot, this time with gumout all-in-one. While Seafoam won't hurt, not sure how much it will help being mostly Pale oil. The 20% IPA (Isopropyl alcohol) may boost octane levels so it could run better till the tank of gas is gone and you refill.