truck runs bad

Sounds like your truck needs a lot of TLC. I would start with the battery - have it tested and charged. Not with the Alternator, with a charger off of the car. Clean up all the battery cables and ground connections you can find. Getting a MAF code is well and fine but it doesn't tell you what's going on - only that the MAF has readings outside the design limits. Just changing parts because of codes is a bad - and expensive idea. What engine is in the truck? A v- 6 I take it from the "Lean bank one". Clean up the battery and such and start over.

check wiring harness to and from fuse panel

Cheapest first... check battery cables, clean them and look for any cracks/corrosion along the insulation (red/black wire cover). Basically, start at battery terminals, work your way back looking for any obvious signs of damage (wear/tear, looseness, maybe animal bite marks, maybe accident damage, so on...). Next, have a local parts house check the battery and alternator... Autozone or Orielly's usually does this for free, or if one near you (or your favorite) might, too. They can check these items without them being removed. Also check fuses.