In Summer: Engine starts, idles properly, car drives with no vibration. In Winter: Engine catches then dies. Depress gas peddle slightly first then car starts but idles slowly then after ~15 sec picks up idle speed. Car drives with loud vibrations from engine transmitted thru chassis. After engine warms up and sits with engine off for ~15 minutes, will start and run like its Summer (see above). Depending on outside temperature car will display appropriate degree of this problem. i.e. in cool weather will start first time then display lesser amount of “Winter” characteristics. Coolant and air temperature sensors tested OK.