bad gas is doubtful, more likely some other issues within the fuel system that the higher octane additive is aiding in overcoming. check fuel pressure, change an old filter, check the sock, check voltages to the pump, etc.

diesel is an exception to bad gas theories since it is much more susceptible to diluting with water. with gasoline water will settle at the bottom of the holding cell and in most cases is never touched unless the station is late on a delivery or has a serious issue with a rotten holding tank.

 

Any news on this? my car is doing something similar. But it tends to only do it when it's cold, and full throttle. misses really hard about 3k rps and goes away above 4k. Thank anyone in advance, this thread was the closest resembling my problem i could find.