Pontiac Repair: 350SB Question, bf goodrich, first 30 minutes

Question
I could sure use a sounding board on an issue that just came
up with my 72 Stingray.  

The rebuilt 350SB has just 2500 miles.  The carb & fuel pump
were replaced 2 yrs ago. The motor has always run well.

I have not driven the car for about 3 months for need of new
tires. I finally got around to putting on a new set of BF
Goodrich T/A's last week. That solved the vibration issue.  

No sooner than I get a big smile on my face about how smooth
the ride is on the highway, out of the blue the engine faded
very suddenly in power and shut off WHILE driving 60-70mph.  
Fighting the lack of power steering/brakes, I eased off the
road to a stop. The engine restarted after a few quick turns
of the key. I figured it was fluke...perhaps some bad gas. I
topped off 1/2 empty tank and drove home w/o any issue.  

Turns out it wasn't s fluke.  

Today the exact same thing happened to me 3 times in the
first 30 minutes of driving (again at HIGHWAY speeds).  I
whipped a U turn off the next exit and prayed I'd get home
w/o getting rear ended.  Fortunately it didn't shut down on
my way back home.

Until now the car has otherwise run great.  Even now the
engine seems to idle perfectly, the choke works, and the
throttle response is otherwise spot on.

When the problem happened on the highway I could feel an
immediate drop in power and motor shut off promptly. That
process happens in about 3-4 seconds.

The bottom line is that it's never just shut down on me
(EVER) at any speed once it was warmed up.

After it shut down I didn't smell gas. I had to crank it a
few times, but it started up within 20 seconds and appeared
to idle/accelerate normally, but inevitably ended up
shutting down without warning, again at a highway speed.  

Obviously, I need to diagnose this problem and fix it before
I take to the roads again (else risk a bad accident or
worse).

If you had to take a WILD guess, what do think the problem
might be ?

If it was shutting down at low speed or idle I'd probably be
more inclined to suspect the carb, but the engine is
shutting down w/o warning at highway speeds.  I don't smell
gas so it doesn't appear its flooding.  I can't be sure
though.  I guess I'll pull a few of the plugs tomorrow to
get an idea on if the carb is running rich or lean

Or perhaps this is an electrical issue ? The distributor has
no points (electronic) stock GM but does have an external
coil. I have not replaced the coil since buying the car 3-4
years ago.  I have not replaced the plug wires either, but
should.  Like I said, when it's running it's running great.

Assuming this is an electrical issue, ignition parts are
relatively inexpensive, but I'd prefer to make some educated
guess at the problem instead of using the "replace parts
until problem is resolved" approach.

If you have some comments/advise I'd definitely appreciate
it.

Regards,
Casey Saunders
Frisco TX

Answer
Hi casey:

this may be a hard one to find being that it acts up and restarts relativly quickly. My guess is it's an ignition issue and the fact that the engine is still running when it cuts out the cylinders load up with fuel and that is why it takes a bit of time cranking for it to clear out ebfore it will catch again. It is more then likley an ignition problem either with the pick up coil in the distributor or the ignition module. Usually a coil doesn act up like thet they either work or they don't no intermittant issues with them. so I would go towards the issue bing in the distributor. The parts are cheap enough for those to just replace them both at the same time and I would venture to say you will have it fixed. It's a heat problem when it runs long enough that it heats up and cuts out. So if you were to take the ignition module out to have it tested it would test good untill it gets good and hot. heat and electronic parts don't get along well. Good luck :)