We would suggest starting with B-12 Chemtool Total Fuel System Clean-Up (part #2616). This product will help remove any free water as well as clean any gum, varnish or other fuel related deposits from your fuel pump, fuel lines, carburetor(s)/injectors, and intake valves. If you still have a bit of a rough idle or some cold-weather hesitation, you may need some additional cleaning. In that case, we would recommend using our Professional 3-Step Fuel System Maintenance Kit (part #2630). It contains an air intake and throttle body cleaner, a combustion chamber cleaner (applied via manifold vacuum through either the PCV valve or the brake booster), and a can of our B-12 Chemtool Fuel Treatment. The kit may sound a little intimidating, but it’s pretty simple to use and even comes with an instructional DVD.