Well now that i have your attention it is more of a slight vibration,
I have 99 GS4 its almost time for my 90k mile service, I have slight vibration sometimes not all when I am sitting at a red light I ve noticed that If I press on the gas lightly while still holding the break it stops I guess beacause the car start to receive more gas will this be taken care of and stop after the 90k service or do I have to do something else anyone please thanks

 

welcome to the club of low rough idle GS4's! it's a common problem that lexus has no fix to it. do a search on our forum and you'll see what i mean. people have tried new throttle bodies, MAF sensors, TPS, you name it, it's been done.

 

thanks GSQS , I guess I dont feel that bad then since everybody has that problem i guess I'll try bananas method but thanks

 

Did you fix it? I'm having the same problem. Thanks.

 

Just putting in my $.02

Was searching some of the forums and came across this.

Might not mean anything but "has anyone who is experiencing rough idle had their stock air filter replaced with a K&N filter prior to the rough idle?"

If so, I wonder if the hot wire on the MAF sensor has been coated with oil form the K&N filter and now is not communicating with the ecu properly.

If so, try removing the MAF sensor (located between filter and throttlebody and clean it out with carb cleaner)

Here is a pic of the MAF sensor location on my RX

 

Try resetting the ECU (remove negative cable from battery for min. 1 hr.). Then re-install....start engine and rev it hard for 10 seconds or so.

Also, I would check all my fluids to see if its topped off. Check engine and transmission oil too.

Good luck.

 

This is actually a good thing to do every once in a while. My MAF was replaced by the dealer and my gas mileage jumped (use less gas). Perhaps, I could have just cleaned it.