This problem concerns a 1999 Ford Taurus 24 valve engine. It has 112,000 miles on the odometer.

After the car has warmed up, the engine begins to miss when idling. I don't notice it when traveling down the hi way.

I took it to a mechanic the other day but it was only a 2 mile drive to his garage and it didn't do it then.

However, after traveling several miles yesterday, the engine missed each time I came to a stop.

I changed the fuel filter last week. It had new plugs and plug wires 14,000 miles ago. I add injector cleaner at each oil change (at 3,000 miles).

The check engine light does not come on.

If it was a problem with the injectors, wouldn't it miss 100% of the time? It is puzzling that it only does it after being sufficiently warmed up.

bernsax; The '99 has misfire detection and should be setting a DTC, if so. Scanning the PCM should tell you. With that said; If it runs okay when cold, but starts running rough when warm, you may have a vacuum leak. When the engine is cold, it runs rich which in turn can 'mask' a vacuum leak. As the engine warms, the fuel delivery leans. But, if it is a vacuum leak, I'd think that the O2 sensors would be picking up on this. Same with a faulty pressure regulator or an injector problem. When you turn the ignition on, the check engine (or service engine soon) lamp should be on, then go off after a few seconds when the engine starts. I'd recommend having the PCM scanned (with live data).
Loren
SW WA

Turned out that it had one band spark plug wire. I'm surprised because the set was new not that long ago.

Thanks for taking the time for the update. Glad to hear everything is 'Good in the world'. Have a great week.
Loren
SW WA