Hei problem I think... HELP

[RainFade]

OK please bear with me here I am TOTALLY new to GM products and I did search the board so to TRY and avoid asking the same stupid newbie questions.

My 71 K20 has an HEI courtesy of one of the two previous owners and I think it has issues.
It all started last Wed (the day of our first really big snow) I wanted to take the truck to work, fired it up it warmed up fine and just as the kids walked out the front door it died INSTANTLY, wouldn't restart.
Jumped in the impala got the kids to the sitter, wife to work then headed home to troubleshoot.
It had no spark, I had a good 12 volts to the distributor (I have it wired directly to ign unfused but also put it back on the connector the PO had wired to the stock harness after removing the resistor wire) but she wouldn't fire... funny thing though after removing the connector to check voltage with my meter when I stuck it back on it fired and ran about 5 seconds then died again with no spark.

At this point I'm thinking module maybe coil, so a quick trip to NAPA for a module cap and rotor (hey while it's off might as well) and big ol tube of silicone dilectrec grease... install it all (while standing on a 5 gallon plastic bucket in the freezing rain) and it fired right up ran great... drove it Wed to work and back drove it Friday several times all told probably 200 trouble free miles.
Yesterday I load it up, warm it up the wife and I pile in and I make it all the way to the street in front of the house... died instantly won't re-fire.
I pull the wire check for 12 volts... got it stick it back on and it fires runs 5 seconds and dies again no spark.

Thinking maybe I have an intermittant coil problem I pull the cover off the coil wiggle wires around and for giggles try to start it... fires right up I pull it into the driveway and it continues to run, I run to the local garage to air up a tire with a slow leak, take her home shut off and restarting all the time.

So before I throw yet more money at this thing I wanted to see if some of the old pros here think my diagnosis of coil sounds right or am I overlooking the obvious ? When I had it all apart I checked the wire from the module to the coil for intermittant opens with the meter and a lot of flexing and it SEEMS ok but I also suspect it at this point.

Interesting side note my new neighbor (I moved in with the wife when we got married in Oct) comes out tells me he's noticed the truck and loves it asks the problem I tell him.. he leaves to come back with an accel dual point distributor and wires and gives them to me... I think I'm going to like this neighborhood

I would GREATLY appreciate any guidance here.

Now for important stuff I hope you all had a wonderful Christmas and a perfect New Year