Springer

Bought a 2003 Is300 a year ago and i've been having the same code reappearing since if i drive the car over 75 MPH. I've installed new plugs, swapped coils three times,swapped injectors from two different locations and resistence checks of all o2 fall within range. If anyone has any good thought on this I would be very interested. Also the car seems to run great weather the lights are on or off. Any thoughts!

HELLO I'm a first time poster with this forum. I bought a IS300 last year,2004 automatic nice little rocket! As I work away a lot the car was parked for a couple of weeks before I had a chance to have some fun with it. As soon as I started to drive it a little harder it coded up P0300,P0303&p0304 random misfire on cylinders 3&4. I'm a helicopter mech. so I purchased a good quality code reader and proceeded to try and figure out the problem. I changed plugs first, no change,swapped coils all locations 2 times and wires were changed , still no change. Removed intake and swapped injectors, it still codes the same. This leads me to believe that I have a faulty ECU, has anyone had this problem or something similar any info would be appreciated. Thanks Richard