01 Ford Escort ZX2 Changed plugs one at a time correctly gapped but now very rough idle sputters and check engine light is on?

If the check engine light is on you can bring the car to advance auto parts and they will, hook your car up to a machine that will tell you exactly what you need to replace for free If you used CHEAP plugs this will happen. My 98 ZX2 did the EXACT same thing When i put in the cheap plugs. Put the more expensive ones in and problem solved. I would go with the Motorcraft (ford) plugs about $6 a plug...Worth it because you'll see a dramatic increase in your gas mileage.