Probably a dropped plug. They crack easily. Try replacing them again. The gap isn't that big of deal so the "quarter" style ones do it just fine. Finding a wire-style gauge in that large of size is harder but all stores will stock them on their tool aisle. They're a pain to use however.
It's still happening after going back to denso all gapped at .50 t/k thought it could be the tires being out of balance so we rotated them and it's still happening...my tires are almost bald it's bucking really really bad at 50 in 4 th gear on a freshly paved road. My friend took off my throttle harness to try and figure out whats ground and power to test my throttle volts before and after grounding my t/b to the battery. Could it be a fuel filter? I keep changing gas stations from circle k to chevron to bp. cars got a little under 30,000 on the clock.
oh I also did the big 3 all with 1/0 gauge wire could it be a bad ground? Alternator to subframe battery to alternator and of course battery power to the back of the alternator and yes I did grind away the paint on the subframe so it gets a good connection. I did not remove the stock wiring I kept it intact obviously LOL
Moved to Ford Focus Technical Chat. That's the forum for imminent auto destruction and repair.
Merged with your other thread so we're all on the same page.
Your problem is most likely the TB- yay FBW. No big ground wires will save you from FBW problems. Replaceable TPS's seem to be much cheaper in this respect. You could try cleaning it with MAF cleaner, but I'm not sure if there is somewhere that you can get inside to the motor- or if that would help at all. It seems as if it's worn out around the throttle position where you'd sit maintaining 50 mph in top gear.