02 GS300. Roughly 67k miles. Car starts and idles fine. When I put it into gear, nothing seems to be out of the normal. When I go and pushed down on the gas pedal, the car would rev but would not move OR barely move. If I keep stepping on the gas slowly and allow the car to slowly pick up speed, it will eventually run like normal. But if I leave the car alone for a few hours or overnight, the problem would come back. What could be going on? Thanks.

 

Check your tranny fluid. My guess is that it's low...?

 

I'd say mixture of tranny fluid low or needs drain and fill plus sucky drive-by-wire throttle control, mine does the same thing.

 

Yeah, sounds like low transmission fluid level and/or clogged trans filter (you have to drop the trans pan to get to it).

 

I checked the tranny fluid when the car's been sitting overnight and the fluid line is between the two notches. Is that ok? Should I recheck with the car warm up?

If I need to get to the filter, how would I go and do that?

 

Car should be running and the trans fluid warm when you perform the check.
Take the transmission pan off and you will see the filter. Can be a pretty messy job.

 

Maybe your Catalytic converters are clogged? At on etime my car would not accelerate no matter how much gas I gave it. AT first, it would be slow, then pick up speed. Later, it got worse and would go past 10M.P.H.

 

You did not check this correctly. First, let the car come up the temp (drive it around for 10 min or something) then park it, go through all the gears (Park all the way to Low) and back again. Then check the trans fluid.

New trans filters on these cars are normally not required.

 

Plus 1 for a clog cat. But at your mileage its rare.

 

Ok, I'll check the fluid again with car warmed up and update you guys. Thanks.

How much would a filter normally cost?

 

Filters run about $30 but you'll also need a good amount of trans fluid and I recommend using only Toyota/Lexus trans fluid.

 

Mine does the same thing too when the battery is low due to listening music with the motor off.

 

could be your fuel pump

 

Quote by Tinman sounds like he hit the bull's eye!
I've recently had a transmission fluid changed (not at the Lexus dealer), and the filter was not changed. He told me the filter doesn't need to be changed and won't change it..b/c of risks...?

Anyhow, I changed the trans. fluid and that was it...runs well btw.

 

It can be throttle sensor, fuel pump, cat clog, low tranny, it can be anything basically. Just let a mechanic inspect it.