2000 Stratus: Cylinder 1 misfire

Out of nowhere, while driving (as reported, not my car) engine starts stumbling at idle. If you keep the RPM up, it smooths out.

Error code P031: Cylinder 1 Misfire

Details;
2.4 DOHC,
Less than 1/8th tank gas,
Temperature has been mid 30s', but now is in the mid 40s',
60k miles,
Plugs changed in the last year (AFAIK),
Orginal cables & coil.

This didn't happen after sitting overnight so I ruled out condensation since it was driven for over 15 minutes when it was noticed. The plug cables are less than 6 inches in length as the coil is right there. I'm wondering about condensation within the gas tank, but if that was the case, why just one cylinder misfiring, why not all?

I didn't check for spark since the 'boots' are overly long with the plug sitting well below and center of the intake manifold.

My thoughts other than condensation from the fuel tank;
1. Bad plug(s),
2. Bad cable(s),
3. Bad coil,
or
4. Bad injector.

Ideas?? Thanks in advance.

pull cyl.#1 wire off plug and check to see if there is oil in the hole with the plug if so you need vaulve cover gaskets and spark plug seals or swap the wire with another cylinder and see if the misfire moves with the wire maybe a bad injectoralso

Replaced plugs, no change
Swapped coil, no change,
Replaced cables, AOK!

The one & three plugs were black, two & four were ok. Why didn't a code for #2 cylinder show?