knocking on acceleration

I have a 1985 Chevy S-10 with a 2.8 L V-6. The truck has been running rough lately and so I checked it out last week. What I found was a big whole in my vaccuum line leading to my deacceleration valve. I replaced theline,
the PCV valve, and then shot some B-12 into the carb to clean it out. Now when I accelerate the engine has a terrible knocking sound. The sound doesn't seem to be noticeable at idle, but only when I accelerate. The knock is very loud and seems to come from the carburator. When I accelerate quickly in recession there is some type of gas that is blown back through the carburator. I hope someone out there can help.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file
Upload is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.