I feel like I messed up bad - new to me truck issues after purchase

[IT Cowboy]

I feel like I done messed up A A Ron

I bought a 72 C10 heritage edition today with a 402. The truck is nice, no rust I could see anywhere and it ran and drove great on the test drive. I didn't take it above 40 on the test drive though.

It was running fine on the freeway on the way home and then it started sputtering and surging after about 15 min on the road. It would act like it wasnt getting enough fuel and surge in rpms and power. If I put it in neutral going down the road and revved it is would rev ok. If I stopped and left it running for 5-10 minutes and then continued it would run ok again for the first 5 minutes or so and the start surging and sputtering again. If I was idling it didn't surge and if I shut it off it would start up right away no problem then idle fine. There is a mountain pass on the way home so I pulled over and found a mechanic shop close by and left it there for them to look at. I might need to have it towed to a classic car mechanic to have it diagnosed

It was not too warm outside today and the heat gauge stayed about 1/2 while moving. I am disappointed with myself and feel like a kid with a new broke toy. I keep telling myself it probably isnt anything to serious or expensive.

So far I am thinking it might be one of these things

fuel tank vent clogged

fuel pump

fuel pump pressure tooo high

distributor

timing

coil

points

plug wires . coil wire

carb body valve (name?)

clogged fuel filter

vacuum leak

manifold gasket

Any ideas on what it could be or things to check out