I have a 170k mile 2004 LS with the 6-speed. I notice when accelerating from a slow coast - such as right turn on narrow streets, or rolling a stop sign - the transmission revs up more than it should. There is no lurch in acceleration, so it feels like slipping. However, there is no slip when accelerating from a dead stop, and no slip when shifting between higher gears. I haven't noticed harsh shifts either.

So far I haven't found anything about this specific problem in LS430 forums. Any ideas?

I haven't done anything to the trans yet. Unfortunately I can't rule out the possibility that the trans fluid has never been changed.

 

Sounds like it is in a higher gear. Try disconnect the battery to reset ecu memory as these cars are terrible remembering driving habits and stay in higher gear unless you floor it. When you stop it auto starts off in 1st gear.

 

i think this is normal. mine does this sometimes, i think the transmission downshifts itself thinking you are coming to a stop, and then you hit the accelerator, the trans has to shift up quickly to match the car's speed