Ok, so I have a question for all of you. I have just recently started getting these two codes P0827 (up down shift switch circ. low) and P0101 (Mass air flow circuit range/performance). The thing that seems odd to me is that these codes are only thrown right at startup, or a few seconds after. Usually it will do it if the truck has been parked for about 30min-1hr, and restarted, like a lunch break etc. I am going to clean the mass air, as a first step. Can anyone lend any more insight on this? Thanks for any help you may be able to offer.