Own a 2003 LS430 with 130K. Took a 3300 mile trip from Mobile to NYC and back and aboutl 500 miles from home on return trip started running a bit rough. Autozone checked blinking engine light misfire Cylinder 4. Need new coil. Got home replaced the coil. Engine light stopped blinking. It's been on for most of my ownership due to Oxygen sensor which I won't change. Ran for about 2 weeks and now misfire his happening again. This time cylindler four and then misfire on 5 and !. Replaced cylinder 4 coil with Denso and took back cheaper Duralast. Even with Denso same error: misfire 4 and 5 and 1. Noticed oil in the spark plug chamber and some oil leaking at rear of engine at valve cover. At one point in the trip the water was low an engine oveheated a bit. Waited and filled up radiator. That is a mystery with the radiator. Replaced it with OEM. Seems to hold coolant but then inexplicably it leaks somewhere. Probably need new valve cover gaskets and plugs and coils...

But does anyone have experience. Me no likey rough running engine and I'm sure Lexus no like as well.,

BTW first time to post on this thread. Also, I've owned about 10 Lexus from es-250 to ls 400 and a few 430s. Pretty familiar with the reliability, comfort, class and ride.

 

Seems like you know what to do, I would do the valve cover gaskets first, then replace all the ignition coils and spark plugs with new OEM. Clean out the oil in the spark plug slots and you should be good, I had to do the same recently.

I buy all of my parts on Lexuspartsnow.com

always check eBay for some better deals, make sure it’s legit of course!