Is it normal for the LTFT to vary consistantly anywhere from 6-10%. Monitoring them this morning I saw that while at a steady cruise one sided was reading -5.6% and the other side was registering -4.8%. When throttle was applied they jumped to almost even. The reason that I am asking is that I recently started getting the p0420 code. I can clear it and it will not appear for 2weeks to a couple of months. If I don't clear it, it will stay there?