Originally Posted by
Sherminator
What is the mileage on the car? Any odd sounds from the engine? To determine false or actual knock, cut the timing down by a sufficient amount like 10 degrees in the suspect areas, confirm good premium fuel(no additives as most off the shelf ones are junk and your car is mostly stock so not needed). If you still have it then it's a mechanical problem ie plugged cats, bad sensors(knock, MAF), bad fuel injector(s), mechanical noise(valvetrain, loose exhaust, loose drivetrain items)
Try one thing at a time and see the results.