Just fixed my LS400 this weekend, replaced the plug wires, plugs, cap and rotor, started the car and got that pesky miss fire and 2500 rpm. Went back down and worked on the timing belt by way of the timing belt tensioner and did check the timing allignment cams and crank shaft. Turns out the the miss did come from a miss alignment of the cam and crank shaft. We fixed the problem after 2.5 hours of work , the car now runs great again. No more engine light or traction control light blinking.
Thanks alot guys it was a timing miss.
Brent.