75 GMC 250cid won't idle

I have a 75 GMC 3/4 ton 4x4 4 speed. It has a 250 cid that is not the original engine. This engine has the integral head. It has a Rochester Vara Jet II carb. The head gasket was replaced due to leaking and the carb was rebuilt. Timing checks ok. New fuel pump, fuel filter and lines It will not idle, as long as you keep it reved up to about 1200 rpm's or so it sounds great but when it idles down it will die. Every once in awhile it will stay running but idles rough. If, when adjusting the rockers if they were tightened to much would that cause this problem?
All so the wire that goes to the choke, is it hot only when the starter is engaged?
Any help will be appreciated.
Thank you.