I managed 556KMs out of my AE101 GT-Z this week - mainly highway cruising, but with a bit of "playtime" here and there I'm really very impressed with this car
I think it's probably your O2 sensor thats the problem too - same thing happens on the GT-Four when it goes. Good news is that these days you can get cheaper pattern parts that work just as well but don't cost so much, so hopefully shouldn't be too much of a problem to fix Just to be sure though I'd definitely check all the hoses etc just to be on the safe side
Mark