There is an updated recalibration for DTC codes P2106 and P2135 that is designed to improve the computers ability to process the throttle position signal. Unfortunately, I see this component mistakenly replaced many times. If there are any misfire or MAF/ baro codes, this could be caused by RFI or radio frequency interference. Like your AM radio making static noise near an electrical transformer, a component such as a failed ignition coil could be producing an erroneous code using RFI. These concerns are a trick bag, so be sure to tackle all other codes before chasing down the throttle body. To answer your original question, the repair costs to replace the throttle body would be around $350-$500 dollars.
Hi Brian...i am having this exact problem with these two codes on my 06 LS after having replaced coils, plugs one O2 sensor and a pedal sensor assembly. Next up was to be the throttle body. How does one get this updated calibration? thanks in advance for your help!