Sudden Idle Issues with Quadrajet

[dz1087]

So last night after packing up the kiddo from baseball practice, I cranked the truck, let it sit in fast idle for about 60 seconds or so and gave the throttle a tap to take it out of fast idle. Drove it to the end of the drive for the baseball field (about 70 yards). When I came to the stop sign, the engine sounded like it was about to die. Idle was horrible, and RPMs were low enough that my lights were dimming. Gave it some throttle and it picked up and ran fine on the way home, except at stop lights where I had to keep some throttle in and brake with my left foot.

Drove perfectly fine on the way to practice.

I immediately thought vacuum leak, so I looked at all my hoses once I got home. Did not notice anything amiss. This carb was rebuilt by QuadraJet Power just 1500 miles ago. I had it adjusted to run fine in the truck and was happy with the performance of it. Then this happens all of a sudden. Any ideas?

Specs:
stock rebuilt 350
stock rebuilt quadrajet
stock replacement fuel pump
fuel filter before fuel pump