Yeah thats not good.
My car had about the same amount of miles on it when I got it. Thats how mine started the SES light started flashing at me and I just had random misfire cylinder #1, I could reset the code drive around in town for days and no SES light, but as soon as I got on the highway it would kick on after a few miles and would flash randomly. I replaced plugs, wires, icm, coils, injector o rings, harmonic balancer, crank and cam sensor and still had a misfire, then it turned into multiple random misfires. Scanning with Torque showed that most of the misfires were cylinders 1, 2 &3. I decided one day to tear apart the top of my engine and what did I find. My guess is that the piston was already chipped when I got the car and things just got worse as time went by. Before you start tearing apart your engine have you checked the ICM to ensure that it is good? Have you checked for vacuum leaks? Have you given your car a seafoam treatment?