wierd idle noise

i have an 02 gt, and my idle sounds wierd compared to other v8's. i have the diablosport tune installed, with other bolts on, including o/r x-pipe and flowmasters. i didnt kno that i was supposed to use premium fuel with the tune on, so for about 6-8 months i ran regular now from idle to about 1100 rpm i can hear a popping sound that someone told me was a misfire. would running regular fuel with a tune mess up my spark plugs? i didnt mess with the timing at all. i will see if i can get a clip if what it sounds like. thanks

as far as i kno the tune does not affect the timing, i have to change those perametors myself. the symptoms still occur with different octane gas, and it has been doing this for over 6 months, so i dont think it is just a bad tank of gas, but thanks for your .02