I just replaced the o2 sensor in my gvr4 and its acting the same way. It idles a bit rough, and feels like its not getting enough fuel. Once i get into the higher rpm's and boost it, its great. Its low RPM's and the get go that is sluggish. When i do a data log on dsmlink, it doesn't seem to be reading correct, and sometimes not at all. It has gone down to .08 volts. Any ideas or solutions?