I drive a 2000 gt.. at cold start ups, the car runs and idles normally,, but once up to operating temperature, I can feel a vibration. i can even see the engine vibrating when I pop the hood. For those who are going to say it may be bad motor mounts, it only vibrates once warmed up. If it was bad motor mounts, wouldn't it be vibrating at all times? BTW vibrations only happen at low RRM's.. Engine seems to run fine at 3000+. Sometimes when I'm stopped at a stop light and I'm in neutral, the car will surge. it will go from 800 RPM's to 950 RPM's and then drop back off every 2 to 3 seconds. Every time the car surges, I can hear a click noise like a pump or fan clicking on (A/C is off). Help on what it could be?? Fuel filter and spark plugs replaced within 6 months. Changed fuel pump and idle air control valve last week. Car was doing this a week before the idle air control valve went out, but I just assumed the cause of my problems was solely from the iacv which completely died on me last week. I just used Sea Foam Spray to clean my intake system and plan to clean my mass air flow sensor tomorrow.