OK Here goes, about a month ago my SC400 was idleing very high but only sometimes. Sometimes it was fine but when it was high it was obviously going into gear very rough and shifting rough. After about 2 weeks of this I took it in and the dealer said he didnt find anything wrong with it. 500 out the window$$$$$So I took it up to Connecticut to visit my mother and the Tranns just slipped like the car went into neutral. Tranny is shot. Luckily I found a good used one 1250$$$$ Now the car starts but acts like it is running on 2 or 3 cylinders. It idles fine but as soon as I step on the gas it sounds like it is flooding out. Like a big WHAHHHHHHHHH and I am at the point of complete frustration. One day I will start it up and it runs like new and some days it runs like absolute crap. Any ideas would be great. Thanks in advance to all!

 

Try the suggestions on this thread https://www.clublexus.com/forums/sho...d.php?t=551125
Try messing with the iacv, tilting the tps, or maybe its just one.of the coils.
Good luck!

 

Also try the 12v fuel pump ecu mod, very easy to do. Just search on the forums. Try it by jumping the terminals on the diagnostics.port, dont fully rip off your rear seats to do the whole thing, well at least until you find out if thays the problem