1998 Ford Escort Escort Sport Check Engine Light Issue

I have an 1998 Escort ZX2 that has a fairly low-mileage of 125 000km I just bought it used in November from a dealer out of province. About early February it developed a problem where the check engine light would come on and periodically flash. We brought it to the local dealer but the problem still isn't fixed. This will be the sixth time we've had to bring it back for the same issue and I would really love to know what's really wrong with my poor car.

The list of symptoms include (these are changes I've noticed in the car): The check engine light coming on and staying on - flashing at first then stopping, then periodically flashing. This can start anywhere between 10 to 230 km after the code is cleared.

Once the light comes on the car shudders on acceleration.

Trouble starting when it's cold - also when it's cold there is a squealing - chirping noise.

The car vibrates more than it did at first when stopped and idling.

What's been fixed:
They've checked the codes in the computer and apparently are getting a misfire in the first cylinder. The wires have been replaced twice, the spark plugs replaced, an ignition coil and the tensioner to the power steering. I've asked about a compression check for the valves but they say it's not showing anything.

I don't know if it means anything but it had a new alternator belt installed in January when it slipped off in bad snow.