Problem with my 72 fleetside yesterday

[wwotr]

OK I'm NO Mechanic, but I need some opinions on a problem I experienced with my 72 GMC Fleetside yesterday.

Drove down the Mountain into the Big City for a set of new Tires.

Truck ran Flawlessly!

Then heading over to the Muffler Shop, I was n the Left Hand turn lane and started to take off.
All of a sudden it was like somebody "Flicked a Switch" and cut out 4 of the 8 Cylinders!
The Trucks idle dropped to about 400 RPMs and when I hit the Gas, I couldn't get any RPM's. No Smoke, No Backfire.
Every time I tried to put my foot into it, it would just "Bog" and I couldn't get it to go any faster. I'd just have to let my Foot up off the Gas and Idle/Coast about 15-20 MPH.
I checked under the Hood and didn't see any loose Vacuum Lines, Spark Plug Wires, Gas Smell, (but like I said I'm no Mechanic).
Its a Vortec 350 out of a 1994 1500 Pickup with HEI Ignition.
Had it towed to my Mechanics. He got in it and it started up, but upon revving it up, it "Sputtered" slightly. He took it for a Drive and jokingly asked me if I was out of my mind. The DID ask me if I looked at the see-thru Fuel Filter (at the time it happened) to see if there was Gas in it (which I didn't).
The initial consensus is Electrical. He's gonna check it out and get back to me.
****, I didn't even drive far enough to get the Paper Sticker off my new tires!

;+(

Roger
"RATIKLE"