My LS400 has recently (since the weather has gotten warmer) begun to have a problem in the mornings after the car has not been driven in a couple days. When you shift into reverse, it takes from 5-10 seconds before the car will move - the engine will rev but the car very slowly moves. Once it does take on off though, you can put it back into park and then reverse again and everything is normal and will continue to be normal for the rest of the day (and even the next day if I drive it every day). But if I let it sit for more than 2 days it exhibits this symptom. It doesn't seem to have this problem going into drive after sitting. I checked the fluid and it looked normal but was about 1/2 qt low. I filled it to the normal range but 2 days later it still had the delayed symptom. Today I took it to the dealer and simply had them change the fluid and clean the filter (or at least they said they would clean the filter screen), but I thought I would just drop the thread and see if anyone else has had this problem and what some possible causes might have been. It is a 94 LS400 with 130K miles on it. It has no detectable problems in forward gears and shifts smoothly at all speeds. It took them about an hour to change the fluid, but since I have read that only a drain plug being opened is required I am wondering if they really did open it to check the filter screen. I once had an oldsmobile exhibit these exact same symptoms (only delayed in reverse) and it was just a partially clogged filter, so hopefully if it was a clogged filter they really did drop the pan and check it. I'll see what happens over the next few days I suppose. Thanks!
Thomas

 

I have seen this problem on one of my Toyota/Lexus typically I leave my vehicles idle about 30 seconds to a minute before driving. Also I then take it easy for about a mile when it is real cold.