318 issues

So I have my 318 running in my car and broken in but for some reason now when I give it gas it stutters and doesn’t want to rev any higher, I played with the timing a bunch but it’s still having problems. I checked for vacuum leaks and I can’t find any but when I put my hands over the carb it doesn’t change the idle at all, and I know it’s getting plenty of gas. I’m 19 and this is my first car build so I’m just a little lost. Any info would help.
Thanks, Carson