Nobody can figure this out

You should have that done. Your engine is on borrowed time. The link below is my timing belt which I had changed earlier this year, it was installed in 2004 so yours is 2 years older.

@Honda Blackbird: You could be on to something there, but I’d also mention that air density is higher in cooler weather, which can offset some problems. It seems like every car I’ve owned has run best when the outside temps are cooler, and have a sweet spot at around 60-70 degrees.

compression test is done, here are the numbers:

Cylinder 1 - 190
Cylinder 2 - 190
Cylinder 3 - 185
Cylinder 4 - 190

Also, attached is a picture of my spark plugs.

Hope this helps narrow it down.

My 2000 Dodge Durango had a bad idle would not idle untill the engine heated up. Then idle smoothed out when cruising at a constant speed engine speed ,but would not accellerate from stop,backfires and missing very bad… replaced spark plugs and cap and wires. no improvement. Checked fuel pressure it measured 7 to 14 lbs , variable readings. Should be 45 psi . Had the fuel pump replaced by garage. Now runs great. In tank fuel pump fabric filter gummed up with brown stuff. Can’t tell what it is.

Have someone spray something like a carb cleaner around the intake manifold gasket. If the idle is affected by this, then you may need a new one, although Honda’s are not known for this issue. Spraying anything around the intake manifold gasket should not affect the idle in any way, unless the gasket has a breach in it. It is mostly affects the idle, under throttle, the manifold vacuum is lower.

keith - I forgot to mention that this weekend I also sprayed starter fluid around the intake manifold and the vacuum hoses looking for a vacuum leak. nothing affected the idle in the least.

The compression numbers are fine and the plugs look decent (as much as eyeballing a modern plug can be) but the plug on the right end looks a bit odd. It almost looks like it’s lean burning due to a vacuum leak or possibly fuel deprivation.
This can lead to a misfire on one cylinder and cause a spark to jump inside the distributor cap which will then affect other cylinders.

Just curious, but after replacing the distributor was the ignition timing properly set according to the underhood specs?

Timing that is advanced too much can affect a plug in the same manner and also may affect one plug more than the others in line. A vacuum leak can also affect one cylinder more than others and just my 2 cents, I still think a vacuum gauge is the best way of finding out if there’s a leak or not.
An EGR fault (which may technically be a leak) can also cause odd problems like this and again, a vacuum gauge would show this.

ok4450 - I’m not sure if the ignition timing was properly set, I didn’t ask.

Here’s an update -

I noticed some corrosion on the battery terminals so I cleaned them off fairly thoroughly, and after reconnecting my battery, the CEL came back on, then shortly thereafter went off, for about 3 days. During those 3 days the car ran like a dream, and in idle the engine purred like a kitten. now the CEL is back on, but the rough idle is not nearly as pronounced.

Does this offer any hints to any of you experts?

I don’t suppose you read the malfunction code(s) while the check engine light was on?