Fresh engine running fine - until last week

1000 miles on my freshly rebuilt engine and it has been running great until last week. Zenith carb with all of the pollution control still in place. Advanced Distributers rebuilt the dizzy with my 15 year-old Pertronix still in place; new rotor & cap; 15 year-old Acel wires.

It would run fine and then just die suddenly at a stop light but re-start immediately. It might die 3-4 times while waiting for the light to change. It might run down the road o.k., but I would let off the throttle and then sometimes sputter and die when I apply the slightest pressure to the gas pedal.

I checked the fuel pump output and I am getting half of a 2 lb. coffee can in 60 seconds.

Now it's kinda hard to start with lots of missing, but I rev it to 2500 and it smooths out to almost normal. It will hold idle for about 30 seconds then the RPM's drop (starts missing) and it dies. If I try to apply a little gas, it bucks and dies.

Today I tried new spark plug wires and my old dist. cap. No change.

I removed the gas cap and it kept running at idle! I could only run it for about 2 minutes because I lost my cooling fan (another story there) but I'm beginning to think I have gas tank venting problem. I believe I can feel a very slight vacuum on the palm of my hand when I cover the filler neck.

Am I on the right track for the symtoms?
What are the usual components to check? Charcoal canister? Anti-run on valve?
How do I check them?

Maybe. I wish I knew what your fuel flow means but I would have to look it up. I cracked a brand new gas tank once because the line to the carbon cannister via the can in the trunk was plugged causing a vacuum that sucked the tank in, then it would let go and finally the tank beer canned and started leaking. I drilled the hole in the gas cap and all was good.

Pull the vent line off that goes to the float bowl vent on the carb, and see if there is ANY change. If you do it while it's idleing, and the idle changes at all you have a venting problem, poss. in the charcoal cannister.