[Jackpine]

First, don't put it in 4WD on hardball! (Even in rain!). You will naturally get the "jerky" feeling if you do. All four wheels are "biting" and they can't all turn at the same speed, especially if you are turning sharply.

Use 4WD on twisty mountain dirt roads with steep dropoffs when you want extra traction, or in mud, ice or snow, or perhaps, when "wading" a creek - but you can easily get swept away doing that, if the creek is running fast enough. Here in Airzona we have a "Stupid Motorist Law" that's been applied to idiots that try to ford running washes. 4WD is not for use in "city" driving (or even highway driving) on wet roads - you have totally screwed up handling if you use it in this case, and you can put your truck in the ditch or into someone else's vehicle!

Next, the fact that you are using 93 octane is of little consequence. You might try advancing the spark on your 91 octane tune by 1 degree, but that is about the only change that's needed. (In fact, it's NOT needed, but you might possibly get a bit more out of the gas with this spark advance.)

- Jack