My 89 Tracker surged for 3 years, only on start up until reached operating temperature. What corrected it was adjusting (turning clock wise) the Throttle Position Sensor... which is located on the throttle body. Loosen the two screw just enough to turn the sensor clock wise. Then retighten. Start up check the performance. Move it aprox 3mm at a time. This worked great for me .. Absolutely no more surging.