I have a 98 Chevy with 16xxxx miles in it. I was driving one day and it started missing. I ran a scanner on it and the codes that came up were the Bank 1 sensor 1 O2 sensor, egr problem, and cam/crank correlation off. So I unplugged the egr valve and it helped a little but it still ran bad. I tried turning the distributed ahead and back but I can only get -18 or 36. Is it possible that my timing chain jumped?