sounds like a faulty newish plug .
even if its Bosch.
what I like to do is watch it spark out of the engine ..
ground it with a clip on a jumper wire and fire up the engine ..
often I see tiny sparks leaking to the side, rather than firing across
the electrodes.

sounds like a funky new spark plugto me.
I kinda only believe in single electrode spark plugs ...either
conventional or platinum.

interestingly ..
on my most challenged for firing the plugs cleanly car ..
a 41 year old carbed mercedes..
what it likes , and does not wet-foul spak plugs on is ..
subaru spark plug wires and modern subaru type spark plugs of the 5/8th
inch hex size ( same 14 mm thrad ) ..and used onesat that, includign the
soobie plug wires. They don't wet-foul in that very old engine. fwiw.

good sluething on finding your promblem !
scott
turbovans

On 1/13/2013 11:01 PM, JRodgers wrote:
> I have never in all my years of maintaining engines had a spark plug
> that just plain quit. But it just happened.
>
> Running fine - then suddenly rough. Started that tests. First looked at
> the distributor - near new. Next tested the lead by running the engine
> and putting a strobe on it. totally dead. Pulled the plug, check the
> electrodes - near new. Put the plug back in. Got another known good lead
> and installed it. Checked with the strobe - stone cold dead!! Only thing
> left = dead plug. Replaced with new - fired right up running smooth. I
> have had distributor caps go dead on one plug, I've had many leads go
> bad or dead - but never a spark plug - not like this - stone cold dead.
>
> Like the Lil' Boy sez _"Larn sump'in new every day!"
>
> John
>