One data point for you - I'm not an expert. On my 99 Rx300 2WD I had been experiencing some jolting - more on starting than stopping and when shifting from p to r, n to d, r to d, etc. starting around 90k Also had check engine light on and off for a while. Codes suggested Oxy sensor and Throttle Position Sensor. After having replaced, have not experienced the jolting. Other posts in this form discuss changing the Throttle Position Sensor - not overly complex - I did not do it. Not an expensive part. Just turned 109k.
FYI.