Alright guys, same issue.
I broke down and ordered another carburetor, a National. same brand that the previous owner had on the truck when i bought it, and it's giving me the same issue.
It's really making me wonder if it's just these junky National carbs (both have had the fuel cut solenoid go out on them, the solenoid goes wacky even when bench tested on both) or if it's another problem.
i put in a 1-4 psi fuel regulator with no noticable change today, still going to try and adjust the pressure a little bit lower to see if that can fix anything.
I can smell excess fuel when it happens, could possibly be weak spark? I don't know how to test for that besides just replacing the coil. I've jumped out when it starts to show it's symptoms and checked the float level, but it always seems right in the middle of the glass, or just below (seems normal as ever). I would love to get my hands on a factory carb just to see if that changes anything.
update on the problem:
the issue happens on and offroad. on the street it only ever happens when we have hot weather, I run the engine till its warm, park the truck for about 10 miniutes or so, start the engine, normal idle. go to take off in 1st and engine sputters, lurches and wants to die at low low rpms. i get the engine up at higher rpms for a mile or so and the problem goes away completely.
The problem happens most of the time offroad, when i'm just crusing around on trails, doing low speed crawling it does the same thing. seems like a lot of bumpy terrain accompanied by slow lower rpm driving causes the problem. Again, the problem does not go away until i hold 25+ mph/ 2600 rpm ~ for a mile or so. I've tried to sit in neutral at a stop and just hold the throttle open thinking it needs to burn extra fuel out of the carb to no avail.
i'm gonna continue to play with the adjustment on the fuel pressure regulator, but would love some more input from you guys.
Edit: with the new carb the truck isn't sputtering on downhills like it was previously, so it did fix something
