Just weird that the Leads all have good spark but when plugged on, two missfire. If you took a Spark Plug out now, what colour is it? Correct electrode gap?
Does sound like a coil pack, but i'd still check everything else first.
You'd need to plumb a fuel pressure gauge into the fuel line, i know bigger cc Zetecs have a bit in the fuel line where you can just screw a gauge on, but i don't know about the 1.25 Zetecs, i presume they would.