[ex_burst]

I was driving my truck around 3-4 days ago and suddenly the gauge cluster died. I pulled into the nearest parking lot and it just happened to be an autozone parking lot, had one of my batteries tested and they said it was bad. Replaced it, truck idles at 800 now, battery light still on but drove home. Got to my apartment's parking lot, turned truck off and decided to see if it would turn back on, it didn't. The only stored code is P0884 for the TCM. Jumped truck to drive my sister to work and right after I dropped her off, gauge cluster shut off an the truck couldn't get out of first gear. Hobbled the half mile to Walmart, got another battery and went to orielly's first thing in the morning for an alternator. Replaced alternator and the truck still has the battery light on and idles high. Looked for worn wiring and couldn't find any, what's my next step? Also first post on this forum so I'm sharing a pic of my truck for everybody.