My '08 250 definitely has the vibration stop when I switch on the lights or a/c as the idle then kicks up slightly. The dealer witnessed this, did the carbon fix but vibration came back soon after. Is there some other fix? I have always used Chevron premium

Ask the dealer to check the engine mounts.

My '08 IS250 has about 38k and this started happening. I had a sudden loss of power while I was making a right hand turn, like my car was having a fuel issue. It happens about once a month. I always use Shell V-Power......sometimes a little red line!!! It reminds me of my idle air control valve that went on the '96 toyota camry...at least somewhat.

never experience vibrations until i replace my exhaust but its not as the steering wheel and some of your body parts will make a rattle sound,went to dealer and explain to me and try to put back my stock just to compare and link the problem but decided to put back the upgraded exhaust and time pass by it disappear al of a sudden,been driving this car for almost two years now and i never experience any vibrations,the mileage of the car when i put the exhaust is 35t and now it's 50t miles on daily driving.

apparently, all the other techs at my lexus dealer do when a customer comes in with this complaint is put in a bottle of top engine cleaner. i bought a GS 350 AWD yesterday and i am experiencing this issue. when i pull up to a stop light and put my foot on the brake, i usually rest my left arm on the armrest. while doing this in the GS i felt a small vibration under my arm, my butt and my girlfriend said "does this car have a massager in the seats?" i laughed, but then realized this is exactly what they are talking about at work. i will be going to work tomorrow, and you guys can guarantee i will be getting to the bottom of this issue. i believe it is build-up from the DI system, but i am going to work as hard as i can to find a more permanent and suitable fix. i will post some of my results in the next month. i love this forum and i am going to contribute as much as all of u have. thank you for all ur info, and i will sure to get somewhere with this problem.

any update on those vibration?im planning to get the bc coils but im worried about this vibration since i have the is250 awd.i want a smoother ride but at the same time dropped.would it be better to get the new revised f sport spring but the drop is hideous or get the bc coil and suffer the vibration?

glad to have an inside guy like you on the forum.. someone who may be able to get a lil further with the techs about the issue. let us know!!

The coils have nothing to do with this issue. Some people are confusing a different vibration issue related to lowering the car vs the engine vibration issue apparently due to carbon build up.