Hey guys ! So I recently purchased my FG XR6 Turbo, It is bone stock only 40,000ks with a mature previous owner. now after only just getting it home and pulling up at the local service station only to notice that my MIL or engine light was on, and the idle had become very rough, consistently reving as if I was driving a v8 with a very lumpy cam. So I took it to my mechanic and he said that the timing had advanced its self to far, and suggested to run 91 octane fuel so it would pick up on the nocking and pull the timing back its self.. now I have given a small amount 91 (not wanting to put to much through) with no luck as of yet. Has ANYONE has this problem before? or can anyone shed some light on the possible Issue, as it is driving me insane. Thanks heaps !