Fuel Pump or too much heat?

[rman45]

I have a '73 Blazer. Just put in a 454 from a '75 donor, that runs really good and is probably stock, perhaps a mild RV cam. Just put a new Jet q-jet carb on, and replaced pump to carb fuel line with Russell Flex fit blue rubber 3/8" hose, fittings, and a new in line Russell fuel pressure gauge. The problem I am chasing only happens after driving for a while, and I would guess outside temps are around 85. The engine runs awesome in the cool mornings. The problem comes when it gets warm. The engine want to die. It happened one evening, I pulled over, looked down the carb, shot the throttle and it didn't spray any fuel. A little starting fluid or gas, and it'll start right back up and keep going until it decides to act up again. I can make it happen by demanding more fuel with the secondaries, or it may do it on it's own at an idle or in cruise mode. My new fp gauge reads from 3-5 lbs while driving... sometimes. This morning, I removed the long line that fed the gauge inside the cab, and installed it directly to the "t" in the fuel line, just before the carb. The gauge first read 3, then went to about 4.8, then dropped to under 2 lbs and stayed there. I suspected low fuel pressure and purchased an electric one last night to supplement the mechanical, but now second guessing that idea. I also noticed that the headers are very close to the frame rail and fuel lines, near the front shock mount, and that the fuel line coming from the pump was slightly touching the lower radiator hose. I need some advise or ideas about solving this issue. Thanks guys.