55.2-59 Not sure what my Trucks issue is - HELP!

[2bo.c10]

Hi Everyone - having an issue with my 1958 Apache with a i6 235. At idle, it runs ok but has some crackling and I can rev it and it doesnt "die" when I depress the gas pedal. When I put the truck into gear, however, and give it gas, it wants to backfire, sputter and cough and die. I have to engage the clutch and feather foot the gas to prevent it from dying. Here is a video of my truck and what it sounds like.

https://youtu.be/chzixjkwW7s


Here are some points / things I've tried:

1. DISTRIBUTOR: I went to HEI a few months ago and it didnt like it so I went back to my original distributor and points. Truck seems to like it better. When I originally removed the distributor, I didnt mark it or do any of that smart stuff - I just pulled it. Same when I removed the HEI. To get it to fire up, I had to find TDC, the white BB on the fly wheel and make sure theyre in sync. I think I did this right but I may not have. I used a timing light to set the timing to the white BB. As I mentioned above, it sounds like its possibly misfiring. There is a popcorn sound in the exhaust at idle and when it revs. See youtube video link to hear the truck. Someone suggested I may be 180* out of timing. Does this sound like it could be the issue?

2. CARBURETOR: I had the carburetor professionally rebuilt at a place that has carburetor in their name. I assume they did it correctly, but open to the possibility they didnt do it right as I get a little bit of gas leaking from the front of the carb and the gasket seems to protrude a little.

3. VACUUM ADVANCE: Vacuum advance and advance line is brand new.

4. SPARK PLUGS: Spark plugs are brand new and through a spark plug tester, I confirmed spark to all spark plugs.

5. FUEL: New fuel pump and in-line fuel filter. Gas is visible in the filter and seems clean and has no particulates in it.

6.INTAKE LEAK: I put new intake and exhaust manifold gaskets in last week. Today I tested to see if there was an intake leak by spraying WD 40 a the intake ports to see if it would make its way into the manifold and "rev" the engine. It did, but tightening the bolts holding the intake and exhaust manifold fixed that.

7. COIL: - Coil is brand new High performance coil.


I'm really at a loss of what to do. It sounds like it wants to run when I rev it, but once I try to get it to go anywhere it loses power and wants to die.