1999 Ford Escort Intermittent Miss

IF this is on just one cylinder, I would highly doubt that a pcm would resolve this. As oppossed to powertrain management I would be leaning towards a mechanical type of a problem.

When you checked compression on the particular failure, AT THE TIME OF FAILURE, was the compression good then?
Was there spark happening?
Was the fuel pressure good and as there injector pulse?

Greetings:

Thanks for your kind and prompt response.

In answer to your comment: A couple of weeks ago, the car was exhibiting the aforementioned engine miss. The check engine light did come on, and the code was "misfire on No. 1 cylinder". I checked compressions at that time. I don't have the numbers right in front of me now, but I know all 4 cylinders were reading 150 PSI ± 5 PSI or so. In order to remedy this engine miss, I replaced the fuel injectors, the spark plugs, and both oxygen sensors. Since that time, the car has run OK, with the exception of one warm start, when it had the cylinder miss for a few seconds before clearing itself out.

Also, when the cylinder miss has occurred, there has been no ticking, clacking, or other abnormal noise indicative of a hard part failure (valve or lifter) in the valve train.

Also, in answer to your question, when the miss was occurring, there was definitely a spark to the affected cylinder. In addition, when the cylinder miss was happening, I used a "poor man's stethoscope" (long screwdriver) to verify the clicking of the solenoids on all 4 of the [old] fuel injectors.

Because the problem is very infrequent and intermittent, and because there is no mechanical noise accompanying the miss (when it happens), this is what leads me to believe it is an electronic controls problem. Also, a long time ago (many months), a miss occurred, the check engine light came on, and the code indicated a misfire on the Number 3 cylinder instead of the number 1.

I did not measure fuel pressure, but assumed that it was OK inasmuch as the engine immediately responds to throttle input during the episodes of cylinder miss (albeit with the rough running). Fuel filter was replaced recently; fuel pump is original.

The pcm driver may very well be bad based on the results. Unfortuanatley you can only test the theory so far and have to either try it try something else.

let me speak to you from experience. you probably have a slight crack in the cylinder head that causes the mis. when it starts it will seem like you have a fouled plug that gets better after warming up. . .anyway, when you stomp on the pedal from a stop the misfire will likely accur as if you have a fuel delivery problem or even a suspect throttle position sensor. after you test them and know that they aren't the problem then pull your hair out or just continue to drive it until it cracks wide open, like mine, and verified the crack/s after removing the head.
all the while, my coolant was dissappearing and i just kept refilling as needed. it seemed to be less during the winter months, coincidental or not.
by the way, as the white smoke finally showed itself, hard-core,(after driving the car for about 3 years with the symptoms and sometimes getting some "smelly" white coolant laced smoke, especially after starting with a few days of sitting) i did a compression test on all the cylinders and they were very good. that did not catch a bad cyl. (bad head gasket or open gaps in the valves seating). a leak down test might have caught the cracks in the 2 center cylinders.
the cracks went from the valves up to the water jacket holes. think critically, the cylinders were NOT dead and certainly not a broken or failed head gasket between them.
just a note of interest, at the end of the line, while i was pouring water/coolant in the radiator and running the car, it was missing like a son of a bitch and shitting out white smoke. as the water from the radiator started to go down(checked it) the car started to run smoother again. . .did this check of "refill and inspect" over 3 days to understand the condition and consequense of it.
after one of the boys went to the junk yard to hunt down a new cyl. head, it took 4 cars to finally find another one that didn't have a cracked head too. by the way, once more, the engine in my escort was a a replacement with only 30,000 on it for the original that had the same problem, and the replacement only lasted for 60,000 added miles from when installed. . . good luck, and i'm sure you know what to do.
sorry, i didn't take pictures to show you the work and also, there was the check engine light and verification of misfire by the code.
i did all the standard replacement intervals with the plugs, wires, . . ., all necessary routine maint. so those were not suspect to the problem.

I had the exact same symptoms on my 98 escort and it turned out to be a head gasket seep. It had no compression loss and the coolant loss was so little that I hadn't noticed. I would suggest looking for a spark plug that is whiter than the rest. I am 99% sure that this is your problem.