2005 LR3 HSE 4.4 with 156k miles. RPM's rapidly fluctuate up and down even when on a flat road under constant throttle, speed and load. For example, RPM's quickly move from 1,250 to 1,500 at 45 MPH. This problem has been ongoing for two years (and driving me a bit mad). The condition is most pronounced when traveling between 15 and 45 MPH. I've never once noticed the condition at highway speeds (above 55 MPH. It feels like the vehicle is searching for the optimal gear as it seems to be quickly shifting up and down (e.g., between 2nd and 3rd gear). The sound of quick shifting back and forth can be heard near rear differential when seated in the rear of the vehicle. Condition does NOT exist when in manual shift mode. Condition seems to be most pronounced when the vehicle is cold and only slight when warmed up. Condition is worsened when climbing even a slight hill or grade. Condition exists even when cruise control is activated. Throttle body was carefully cleaned (very little gunk was found) and problem persists. Mass air flow filter (MAF) was carefully cleaned and problem persists. Air filter has been replaced. No other problems with transmission have ever been experienced with the exception of occasional "lunging" just before coming to a complete stop. Others in forums have suggested this may be a problem with the torque converter or coil pack capacitor. Please share your thoughts as I'm at a complete loss and this has been an unresolved issue on this any other forums for several years. Thank you in advance.