Kingsoup

Have you had the air filter out to check for any small pieces of paper from the filter on the MAF screen? I had the same problem, checked coils, blah blah blah in an effort to repair, was MAF the whole time, bits of tiny foam on the screen.
Sounds like sensor malfunction to me of some kind.

stephen18

i would check the coils, caps and rotors. i bought my LS400 with a busted rotor...the MAF side one thats much harder to get to, and it acted A LOT like you are describing. TEST parts. dont just replace.. gets very expensive. i know from experience unfortunately.