I have a 1977 K5 Blazer and having a little issue I am trying to sort out.

When driving and getting into about 3rd gear, sometimes the engine will cut in and out int and out. If i let off the gas the truck will still idle but if I gas it slowly do the same thing.

I have took apart the carburetor (original carb) replaced it with new parts from a rebuild kit. Replaced the mechanical fuel pump with a new one. I dropped the tank and took a look inside looked fine, I removed the sending unit sock and added a visible inline filter in the engine bay.

I am not too knowledge able about carburetors and guess this is still where my issue is. I put a vacuum gauge to one of the ports and gets constant 16 when at idle. I do notice that the secondary barrels are hard to open by hand i dunno if this is normal or not.

any other things I could check?

 

I am experiencing the same thing on my 77. What ended up being the issue? Was it the carb or the fuel pump?