Hello,
I have a RX400h that missfire at startup, hot & cold. 50% of all startups are like not running on 2 or more cylinders for approx. 10-15 sec. Engine "jump" hard sometimes ..Then running perfect until next long stop.
Lexus workshop and good independent workshop have found no errors with diagnostics (OBD2).
New spark plugs was also put in on last service, cleaning additive in the fuel also don´t work.
The RX have been 222 000 km on the odometer
I have read several places that fuel injectors and coils need to be replaced could that be the error also on my RX?


Photo taken at Olav’s Mine at Røros Copper Works, Norway

 

Mine shook pretty bad after replacing my 6 spark plugs. But, unlike yours, mine stayed sputtering and running very rough. I limped it to the local auto parts store and they verified a bad code (coil pack).

I ended up replacing all 3 coil packs in the rear (under intake), and that solved my issue. No sign whatsoever before replacing plugs. Only occured after I touched the coil pack to install new plugs. I guess once they are disturbed, they get a little picky.

I got 3 new Denso packs off of Amazon. 2007 RX400h.
https://smile.amazon.com/gp/product/B002Y35O0M/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

Cool pic by the way! Norway!

 

Shop may be able to determine which cyl are not running by using an IR thermometer on a cold engine to measure exhaust temperature. Then swap components to see if the issue to switches to a different cyl. Intermittent component failures sometimes don't leave codes. The majority of issues like this are related to coils.