[Fleeting65]

I'm at my wits end, guys, and I don't know where else to turn...

My '65 C10 has been experiencing an elusive and worsening case of bogging, choking, and now shutting down as if no fuel is getting to the carb. Carb is a Rochester Quadrajet sitting atop a refreshed 1970's 'Vette 350 engine with stock cast iron intake under the Rochester 4B. The engine also has HEI.

I've already performed the following over the past several months, but none have resolved the mysterious issue:

> replaced the (OEM) fuel filter
> replaced the mechanical fuel pump (twice)
> removed the gas tank "sock" (even though it was not clogged
> had the Quadrajet professionally rebuilt with all new parts by a carb rebuild shop
> NOTE: It hasn't been so hot that vapor-lock would be a diagnosis, because it did it during Jan/Feb too.
> I just tried starting it again, and it fired right up...but I know what will happen when I drive it again.

It used to run fine following its 2017 engine rebuild. Then, one day I floored it on the freeway from a 60 roll. It hit about 70 and suddenly stalled out and starved for gas. It's been doing that at high speeds since then. I'd let it settle down and she'd run fine at 45 or 50. But now it's been getting progressively worse & worse-- at 50, then at 45, then 40. Today, after installing the freshly rebuilt Rochester, I started it up and it idled perfectly. I took it on the road... within 5 minutes of driving it starved for fuel at 35mph. I tried to nurse it home, but it finally gave up ~2 blocks from the house, and it wouldn't restart. THAT was a first! The fuel indicator shown over 1/4 tank, and I can hear fuel in the cab's fuel tank when I rock the truck. Walking home I grabbed some fuel, then primed the carb, and it started up. I limped it back home at slow speed.

Any thoughts and/or suggestions from the experts would be very much appreciated.