[enkeivette]

I'm with Joe, I remember reading that reddish plug is caused by the type of fuel. The fouled plugs is likely the cause of the slower acceleration.

Another advocate for the cheap Autolites, copper conducts better than platinum. Then again, platinum resists fouling better. Which might do well for you.

If your wires are burned though to the headers and are arcing, you'll feel a rougher acceleration. If you have an intake manifold leak or some sort of stuck lifter problem, the exhaust will prob sound different. From my experience.

If it feels the same just slower, and your fuel filter is not clogged, prob just bad plugs. I doubt your cats are clogged. Your motor is clean and that would happen slowly over time, not noticeably and all of a sudden.