meter your wires....as a rule of thumb, should be in the range of about 5,000-10,000 ohms per foot.
Much higher than that and you're got a bad conductor or end connection.
Lots of times guys will pull on the boot wrong and stress the connection at the plug or cap (or pull the wire directly, bad,bad bad), flex them excessively when installing them (carbon core conductors on radio suppression wires don't like that at all) or not support them properly (oe wire supports) when the engine is running (flex, flex, flex - crack goes the carbon conductor).
They will still run with a bad connection, but spark will break down (ie: miss) as load comes up.
You can also check your cap to wire connection by removing the cap and metering from the cap terminal to the spark plug end. If you have good continuity at the cap/wire connection, it will not add resistance of any significance to your measurement.