I did the spark plugs after all the carb cleaner, seafoam, B12 etc.. I was able to get 100% seafoam, in carbs, let it set 24 hours, run drain refill x2 days, then 50/50 B-12 Chem-tool and seafoam and two other top rated cleaners, mixed them together in a old school catsup bottle with a cone tip like you find in a hamburger joint,... stuck in on my main fuel line.. turn \on the key and let the fuel pump fill carbs.. did this many times, some how got it to run just a bit to get it in the system.. Long story short, it saved a car overhaul time and money. This is just my experience, read over all the advice here, do what is right for you. I AM NOT a tech, but got some good ideas from some really smart folks on here.. Respectfully, MIke