Originally Posted by
rieper
The reason I think it has something to do with the EGR is it surges worse when the engine is cold and what I hear the EGR shouldn't function until the motor is warm Which sensor tells the PCM to turn on the EGR. I have replaced the heat sensor on top of the thermostat
It's a combination of ECT and TPS, perhaps the Engine RPM comes into play as well. Once the engine is warmed up and light load cruising is the only time the EGR should be active.