Does anyone have any advise on what to look for on this little engine? It runs and starts fine after it warms up. When cold it just pops and farts. I used a salamander heater to warm it up and then it will start. I have already checked the glow coil in the intake manifold and it works well with fuel valve opening and igniting. Compression seems good (equal in all cylinders). Any help would be appreciated as the snow is piling up around here!