ive 130,000 on my june04 build ba xr6t and about 250klms ago it started shuddering under load at low revs , I had it at my mechanics for a service before chrissy and it didnt happen for him ( of course ! ) I checked and double checked hoses and little tips on here ( checking threads ) it ended up being the coil packs . since there've been done its been like a new car ! and when it got done they found a split on one of the hoses that was letting extra air in too , running heaps better now .