Greetings! This Is My First Post.... Need Help/advice!

[is350tx]

i just bought an 08 is350 w/ 37k miles. everything runs great under regular driving. but on WOT at about 80 mph and above it will suddenly misfire and cel + vsc + trac starts to light up with the cel blinking. this is also paired with a totally misfired engine. it all goes away after you turn the car off and restart. but on the second incident, the lights stayed on. it's kinda scary when you're passing a vehicle on a 2way road and it misfires. so i took it to a lexus dealership and the first time they diagnosed it they just said it misfired and reset the lights. after a few days i WOT again and there it is again.

so i took it back to lexus and this time they gave me a loaner. after a week and 3 days the advisor called and said the car was ready. so i returned the loaner and got my car. the advisor told me that it was the #1 coil that they replaced and that the diferrence was like night and day. so i went on my way and as soon as i hit the beltway i WOT and boom! lit up like a xmas tree again with all the lights and the hideous misfire. so i quickly turned around and took it back to lexus. the advisor just shook his head and handed me back the loaner keys. he said it might take a couple of days again.

i received a call again today from the advisor and he told me that they found out that the vehicle had previous records from the other lexus dealers in the city and they couldn't diagnose the problem. he told me to just continue using the loaner because they need more time.

i need inputs from other members who had this case and go it solved. i've read various stories ranging from de-carbonize to valves to computer reflash to transmission. any info would be greatly appreciated. thanks in advance!!