750 aed stumble off idle/start

Your dampner/balancer is still functional. But not in top notch shape. So its best to keep an eye on it. Thats what the paint is for. You need to know if the slipping has happened recently or if its been just a tiny bit for quite a while now. If its slipping fast you need to change it. If you can see that it has moved at all say in 2 weeks time,change it. Thats an everyday driver,right?
As for the carb. Adjusting the accellerator linkage wrong is a common mistake. Holley instructions were not written clearly at all. I know its an AEM? carb but when you mentioned 0.015 feeler gauge clearance well that made me think 'classic mistake'. Remove that clearance, make sure its squirting fuel with the slightest touch of the throttle and you should have no doubt that the bog is gone. Then go back to your original jetting. You will be much happier.