Extra Sparks?

[jgknowla1]

OK, I think I've done enough research and troubleshooting now to know what to even ask. Here's what's going on:

I've got an '82 C10 with 305/350 and quadrajet. It has HEI and ESC.

Yesterday it started idling rough - sort of surging, but would be fine with any amount of throttle. No tach in the truck, but the oil pressure would move with the surges.

By tonight it's gotten worse to where it's rough/low RPM and shaking more often than not while idling.

I went though it looking for vacuum leaks and capping off ports, but that didn't help.

I put the timing light on it tonight and the timing seems fine, except that there seem to be "extra" sparks. If "X" represents a flash of the light, here's what I SHOULD see:

X.......X.......X.......X.......X.......X.......X.......

here's what I AM seeing though:

X.......XXX.....X.......XXXXX..XX.......

There are still spells of what looks like normal timing, but I swear that during the times of "extra sparks" is when the RPM drops and the engine shakes.

So. My question is - does this sound like it's the ignition module going bad? It doesn't seem to be related at all to engine temperature.

Any ideas?