Is your rig running better now? Maybe you had a bad intake or a damaged muffler. The type of gas you use should only affect the engine performance, and even with those mods it shouldn't matter. Sometimes running low octane in hot weather will make it ping more, but I haven't ever noticed it with this particular engine. Do you fuel at the same spot all the time? Sometimes your favorite station can get a tank of bad gas. (that's probably only here in Oregon, though, where they don't believe in testing their fuel
)
I've been running a mid to hi octane and I've traveled all over the West. No problems with performance, unless you count the number of times I've needed a few more inches of throttle.
