That was the purpose of finding out if it had headers...if only ONE cylinder/tube was getting red hot, then that would have led me to think a vacuum leak in the area of that intake port. Sometimes, since the main vac. take-off point is in that area, a vac. leak will effect only the rear-most cylinders.
Looks like you found the problem...sux that the intake has to come off, tho...

 New intake manifold gaskets took care of vacuum leak. Car still wouldn't run. Tested new (reman.) fuel pump - it failed miserably. Replaced that fuel pump. Seemed like problem was solved after a couple of 10 min. test drives. I decided to go for a Sun. afternoon drive last weekend. Just after entering the interstate (about 15 min. from home) it started acting like it was running out of fuel.(The tank is full) Engine would barely idle as we limped home. Tested this fuel pump - flow and pressure was correct. I have 2 questions.

the gas tank vents through the charcoal canister with a non vented gas cap, if you plugged the canister lines and still have a non vented cap the the fuel rubber hoses might be closing shut on ya.  

Kinda sorts sounds like a plugged fuel filter that settles after sitting and takes a while to get plugged up again. Ever have the tank down?

The charcoal canister was removed but I left the line open. I even blew compressed air through the line.

How about the small fuel filter inside the (Q-Jet) carb?

I dropped the fuel tank back in August when this problem first developed. The tank was clean and in good shape. I did replace the screen on the pick-up tube at that time. The filter at carb. was replaced recently too but I will check it again.

The return line is to keep from having too much dead-head pressure at the carb, AND it helps cool the fuel so vapor lock isn't an issue.
If you're just looking at the fuel going back thru the return line, it may seem like a lot, but consider that the carb doesn't really need an abundant flow of fuel while idling.
You may need to install a fuel pressure gauge at the carb and drive it, and see what the pressure is when the problem appears. You may also want to block the return line for a test and see if it has any effect,and maybe even leave the gas cap loose.
Have you blown thru the actual fuel supply line from the tank to the pump, or otherwise checked it for restrictions? How about the rubber line from the frame to the pump? Is there a kink in it?

Seems like we're all looking for a fuel problem, when it may not be one. The pressure reading will confirm that. If the fuel pressure is not dropping when the problem occurs, the the fuel system is fine, and we need to concentrate on another area...

I have a Q-Jet and found the problem was the choke getting sucked shut on high RPM. Let it warm up to choke full open then jam your choke wide open with a piece of cardboard matchbook or something similar. Then hammer the thing and see if it goes away. I had my Q-Jet professsionally rebuilt and it acted up on me again this spring at Beech Bend Dragstrip.... Jammed the choke open and no more problems. The guy who rebuilt mine pop riveted the spring tension adjustment on and I have to drill out the pop rivets to tighten the spring tension, which I haven't gottn around to.

Dave

BTW... Don't buy these guys poo-pooing your Q-Jet... It's the best street carb ever....

Dave