You have the same exhaust i have, i have a 02 v70xc though, i like that exhaust, everyone else hates it lol. I been getting same problems, my throttle body is only 4 years old though but one cold morning i went to go to work and i heard a crack like glass cracking, i didn't think anything of it but then the yellow light came on saying reduced engine performance and i could only go 15 mph and i got to a parking lot and just parked it and walked to work, got back and started car and everything was fine and i shrugged it off as it was just the cold, then i went to store and seen a bunch of white smoke coming from my exhaust and got to store and shut off and seen white smoking just coming out of exhaust, it was weird, i thought my head gasket blew or something and i kept my car at store and had my friends help me get it, drove home without any smoke. Now i get the P2131 code in the background and my throttle behaves oddly, my mechanic is telling me my throttle body is failing but its only 4 years old and it is a bosch and so im thinking it just needs cleaned but i think he just doesn't want to do all the work getting it out and it actually does need replaced and him putting it back in and id have to get a new one anyways. I am trying to talk him into cleaning it though.