Oldsmobile - Intrigue :: Random Misfiring / Running Rough And Short On Power

My '99 Olds Intrigue was running rough & short on power. Autozone read a trouble code "random misfiring" (PM3000 I think it was). As suggested, I changed the plugs/wires and checked resistance on all three coils with no luck. Here's the real spooky thing: while driving down the street a couple days ago, the pipe between the catalytic converter & muffler separated, scaring me and sending all the children getting off the school bus scrambling for cover. There was no noise or odor prior to the 'drop out' - is there any chance that the one problems (a catalytic malfunction, or small leak in the area for instance) could be related to the misfiring? A mechanic - before the pipe plummeted - had suggested it might be an injector problem or the intake manifold but I figured that an injector problem would trigger a code.