My wife has a 98 ZX2 with the zetec dohc. The engine light is on, the service station says the code calls out misfire on all cylinders? He says it probably starts out as one and then progresses to all. We have put new wires, plugs, coil packs. anyone else have this problem?

 

Does it actually misfire? You can get a misfire code if the engine crankshaft sensor detects a change in rpm, which it could detect if it was not working properly.
Does the ECM have more than the 03xx codes? Do you have a leaky intake manifold?

Just a few thoughts.
tom