[f5fstop]

Just curious, you haven't installed any aftermarket equipment such as a radio/GPS/CB?

A rough idle can be caused by various reasons, one being aftermarket items added that are causing EMI with the PCM. Other reasons are small vacuum leaks (easily diagnosed with a propane tank), bad plug, injector, leaking fuel in pressurized side of system, contaimated fuel filter, small amounts of water in tank (have you run a can of dry gas through the tank).
Most technicians seem to want to blame the electronics, forgetting about the basics of how an engine operates.
Good techs who really know the basics of an engine are hard to find, and when you find one, you want to tie 'em up and hide 'em in the garage.
It should not be the octane of the fuel, octane only affects the propensity to explode
rather than simply burn when mixed with air and ignited. Exploding is bad. Burning is good. The higher the octane, the more resistant to exploding.
I would be amazed if higher octane solved the problem, but if it did, then I would let the dealer know and have them look at some sensors.