When should the o2 sensors be changed, i got 100k on my 95, it is runnin plenty powerful still, i just want to make sure what stuff tends to go out as the mileage get a little higher, the o2 are pretty much all that has not been changed recently, all filters and fluids plugs wires cap all that great stuff has been done recently, just want to make sure i keep it running good, thanks for the help Dan