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Not really sure how to put in the fuel line pressure gauge on my own.

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just tee it into the line as close to the carb as possible . Your condition sounds a lot like vapor lock as the others have said.
if you are running 10% ethanol based fuel it is known to cause these exact symptoms in older vehiclesdue to its lower boiling point . I have seen several cases come through the shop. A few of the vehicles had see through filters and as the condition started happening the level of fuel in the filter would decrease substantially.

Another thing I have had cause it is parts store fuel pumps that are putting out 11-13.5 PSI. I tried several different brands and they were all the same. Switched to an edelbrock and the problem vaporized ( pun intended) So we are Currently using edlebrocks exclusively( Pricey) and have not had any further issues.
I would agree with the others, time to check the fuel pressure cold and hot.