[31ASlant]

I'm looking for a few suggestions on where to start with my engine issue.
I recently noticed a knock has developed in my engine.
At idle there is a misfire almost like a stumble every few seconds in rhythm.
I have tried grounding out wires with no change to knock.
The knock goes away under light acceleration , but is present at high speed if you really listen for it. Especially if the timing is fully advanced. I usually run at 9:00 or so.
It's a fast knock at idle faster than the engine is turning at. I believe it has something to do with the misfire.
All ignition and fuel items are in perfect working order.
The car drives great and has plenty of power, does not burn oil or smoke.
Runs cool as a cucumber.
The knock is present on start up and through warm up with little change in its audible sound.

I just want to make sure that it's not ready to explode.
Any suggestions I would greatly appreciate.