I too am having poor mileage, barely 200-220 miles per tank with a 13.4 gal fill up. I have replaced the plugs,air filter, fuel filter. Scanned the computer and have no pending or regular codes. Have reset the computer several times. I do not have the idling problem you have, I fixed that this summer by replacing the IAC, this took care of the Moose problem. But now since I have the OBD2 Pepper scanner, I have noticed that I am running lean on bank 2, about 14% Longterm trim on average and bank 1 is running lean about 8% longterm trim on average. I have tried to do O2 analysis but since my PCM will not support all the diagnostics capability of the tool, I can only graph the O2 results and see how well the O2's are switching. So far, it looks as if bank 2 O2 is running leaner than bank 1, the switching does not look too uniform, that is, these things are suppose to go rich and lean uniformly and the pattern I see is that they tend to hang on one side or the other from the X axis on certain periods. Although, they are producing acceptable low and peak voltages depending on the circumstances. Both the bank 1 and 2 upstream O2's do this. The O2 monitors hang on the high side with minimal switching. Not sure if this is sluggish performance or the OBD2 sampling rate is just not the best for this type of analysis. The O2 monitors are running a bit rich. This at times gives me cat efficiency failures (p0420,P0430) pending codes which later disappear after a couple of driving cycles. This shows up in one of the scanner screens as having Rear to front ratios above manufacture maximum limits too but later they go away. Egr also fails test there too when this happens, in the open position test at 82% when it is suppose to be 80% max. Later it performs ok and passes the test. This leads me to believe, that I may have a leak somewhere but I do not hear anything abnormal. Therefore, I am just as confused with this software as I was when I did not have it. Have you had yours scanned?
