Definitely get rid of the boost bottle !! Only thing they do is crack the intake boots. And I can say that from experience!! And they didn't start leaking until 3yrs later , after I got rid of it, when I did some jetting. Either crossover or some PVC caps that fit in boots.
Occasionally you can get a flat spot that seems impossible to get rid of. Not saying to stop trying, just don't drive in those conditions.
Double/tripple check that carbs are clean, float level is correct, bowls on correct carb, all the stupid shit that gets overlooked no matter how many times posted or you've done it.
Hell, even start double checking electrical, won't hurt.