i just screwed i feel like...

answered an add on craigslist on a 2001 chevy z71 for 3200

So i get there truck looks okay a couple of dings ran good had a cel light scanned it said rear o2 sensor and misfire detected on cylinder 2 ... ac blew cold ac shifted hard looked threw glove box found the tranny was rebuilt with corvette servos then i was happy okay cool new tranny..

today i woke up(next day) hopped in truck ac not working... i hear the compressor clickin on and off ever 15 sec or so. went and grabbed my ac recharge kit it was in the red.. but when compressor kicked in it went all the way down to blue... Im just trying to figure out what can it be, and how i can fix it (ac)

and could the o2 sensor cause the misfire ( but truck runs fine no miss)

 

I feel screwed as well. Bought an 83 c10, get title notarized, get to dmv to find out original owner had made an avadavit statement at dmv months before that said he sold the truck to someone else on a different date to avoid fines and flags for dropping insurance and not turning in plate. You would think the notarized title I have proofs he lied to dmv, give me title and issue him fines and flags for making a false statement. Now I am trying to find a cheap donor truck with a good title. I'm beyond pissed.