My engine is misfiring?

1989 Cavilier, 107000 miles, 4 cylinder 2 liter, automatic: Car has been stalling when low RPM, but no codes up (engine light is off) and none in the computer. Weather is cold (-30 to -40 Deg F) Stalls when idle at red light or turning corners. Sometimes at the red light taking off I could tell there was a miss to the motor, and lack of power. Did not do this all the time, but frequently. Took car inside heated shop and checked plugs, all clean and firing. Found no wires damage. Found no obvious problem with anything esle, all looked ok (no vacuum leak, gas leaks, etc). When I ran it after, the problem went away for about an hour. It started with the car in 3rd gear, at low RPM, car would (studder) but when placed to second this went away as RPM increased. I am wondering if this is possibly a bad wire (shorting occasionally) or the ignition module failing? Or something else?

My experience has been that poor plug wire (high Ohms) will casue miss fire at load or higher RPM but may not show a miss at low RPM. This is due to the current through the wires I suspect being higher at load or higher RPM.

This car idles fine, had no miss at load when I had it just out of the garage. If it was a poor wire, would it not show as a problem more consistently?

Some more information. I did find one of the 4 wires (#2 cylinder) that had no resistance. The wire was bad, broken within the spark plug tip. Would nmake contact sometimes, other times not. During my Ohm test it broke into two.

Removed the coil pack and will take to a place that says they can test them. Has anyone had luck with testing the pack? Parts Source claims to be able to.

Follow Up to Problem: The coil pack tested okay and works fine. The overdrive solenoid was faluty but just half the problem. Found number 3 cyliner badly fouled with whitist pink deposits, removed head, found weak part of gasket, replaced gasket, and has been working well for 5000 km so fare. There was also one poor wire (on the #3 cylinder) I changed at the same time.

1987 cavalier
4 cylinders 2.2
Overhead cam fuel injection

How miss started:
Started up in morning to go to work had miss like water on plugs after 5 minutes engine corrected and ran great. End of work day started and same thing minutes corrected.

Next day miss again but it never corrected it's self and still has miss today

What I have done:

Replaced Plugs and wires
Checked for spark to each Cylinder (good)

Compression test

1 - 150
2 - 165
3 - 155
4 - 160

Spark Plugs are BLACK when pulled out. Look like they were in a chimney (fuel related?)

Engine does not smoke.

Any suggestions on next step to diagnose condition?

If it was a blown head Gasket would I get such strong compression tests?

And :)

It is constant at this point and I drove it for 45 minn one way to work if I was getting water in one cylinder I wouild think the other 3 plugs would not be black?