71 340 running bad

No such thing as new X heads. Obviously everything's not "good" as you have running issues. Saying everything is "new" means nothing as new and good don't mean the same thing.
Exactly. It is almost impossible to diagnose this over the phone. THese threads can go on forever with dozen's of hours spent posting suggestions. @bballfan1 you need to find someone local to you that knows their way around old cars.