Toyota Repair: Clunk/rough shift into reverse, lexus es300, fluid changes

Question
Hello, hope that you can help. I own a '98 Lexus ES300. For about 1 month, when I put the car in reverse from park or drive I feel a hard shift accompanied by a loud clunk or thud. When the car is driven for 10+minutes the condition is barely noticeable. Also, when driving in reverse at some speed then releasing the accelerator the car clunks too. I service the transmission regularly (fluid changes @ 15-20k miles). Car currently has 182k on the odometer. Please help. Thanks.

Answer
There may be a problem with the transmission throttle pressure cable, it may be sticking or not adjusted correctly, it's connected to the linkage at the throttle body and should have a small rubber boot on it, the cable should be pretty tight with very little slack in it, move the throttle and make sure the cable goes back with the throttle and does not stick, there is a small metal sleeve on the cable, this sleeve should be a 1mm distance from the cable metal housing when the throttle is closed.If not, the adjustment nuts can be loosend and turned to adust the cable.