There are a few possibilities;
There is an Electronic Load Sensor, (ELS), that will have varying affects depending on situation
Sometimes there is a fuel system management issue. Check for trouble codes with an OBD II sensor. Some posssiblilites there may be;
Speed sensore, O2 sensor, EGR or Mass air flow sensors.
Let me know if this helps.
Wednesday, June 8th, 2011 AT 10:12 PM