My 96' ZETEC had the same symptoms. I replaced the plugs with double plat Autolites and replaced the plug wires with $18 set of Bosch. Ran great for a couple months and then started the same thing again. Two of the plugs had carbon tracks on them from arcing on the porcelain. Cleaned them up and gooped inside the plug boot with waterproofing electrolytic gel. Been running great for 7 months now.
