2001 Civic, 194K miles, original owner. Compression 130-120-130-110 psi

Spark plugs were replaced about 5K miles ago with Autolites gapped at .040" (I know, I know, but they didn't have NGK's or Denso's in stock, so had to make due in a pinch). Car ran fine for about 4K miles, but recently started misfiring on cyl's 2 or 3 (via CEL codes) on a cold startup for 2-3 seconds. Ran fine after that.

I replaced the plugs w/ NGK platinums gapped at .044". Problem went away for a few days (and no CEL), but now it's back. Now at idle (even when warm) it misfires (so says the wife).

Since the spark plug change temporarily fixed the problem, I'm thinking weak coil (they're original). 4 new coils are $240, so figured I'd ask first.

I haven't checked fuel pressure or injectors (but no codes for the injectors). No code for bad camshaft position sensor, so I assume that's OK too. If PCM went out, all spark would be bad, right? I suppose I could switch coils around and see if the misfire follows the coil - haven't done that yet.

Anyone have an opinion on what else to check? Should I just replace all 4 coils?

 

Exchange coils between cylinders 2 and 3 and cylinders 1 and 4. If the problem follows the coils, then buy new coils.