I have a P0171 code that's giving me fits. Can you help me?

What is your question?

I'm experiencing a "pending" P0171 code that'll turn on the check engine light. I have done some testing and have results. All of these are at Idle position: LTFT 24% STFT hovering around 0 to -3%, Intake manifold pressure 24" hg, new O2 sensors .5V and cleaned MAF sensor. The MAF sensor moves with RPM very well. The MAF is running about 3.5 g/s at 680 rpm. I still have to test my MAP sensor but I don't expect that to be bad. I want to know if I'm on the right track? If the MAP sensor test's between 1 and 5 volts then I know it's getting the correct information. The last question is, when I do an emisions test the catalyst, evap, the O2 sensors (sometimes) and the O2 sensor heater prove incomplete or failed; is this a result of a weak battery and if so, could this be causing a problem of the 0171 code?

What makes this problem better or worse?

In idle is usually when the pending code triggers

How long has your 2007 Chevrolet Colorado had this problem?

I purchased the truck a month ago