Does it sometimes feel like it bucks on the eway? like the engine feels like it is sierging for a few seconds.? Also engine serging when stopped at a light? you really need to keep your foot on the brake at a light because you don't know if the engine will sierge. then you could be in the intersection. eventually it will start stalling after you park or stop at a light......If these are some symptoms find out if you need a new MAP Sensor....thats what happened to me and it runs much smoother after I got it replaced.