Ok guys...thanks for the suggestions so far. I ran a scan on the car today, and no codes came up. I tried to check the air/fuel ratio, but the scanner couldn't display it. I also got voltage readings from the O2 sensors, now I just need to find what the norm is for O2's on a Focus to see if those are collecting crap.
The air filter is fine, fairly new, so I can rule that out. I've cleaned out the MAFS, and I'm considering changing the PVC, though from what I understand, it's an absolute PITA because it's buried around the exhaust manifold. I may shoot for some new plugs and wires this weekend, though I dont know how much that would help...
____________________ Proud owner of a Black 2000 Focus ZX3...