I am not the mechanical expert here. But others on this forum like Marlin and Mike are. My little bit of knowledge thinks that what you are doing will not solve your problem.
The factory metal line is run over the intake and up to the carb. Also the factory set up had no carb spacer. The heat crossover as Mike said should also not be your problem. All of the things you are talking about doing are great and may even tweak an extra HP or two, but would not combine to have the issue as you describe it.
I am running a Speed Demon on a Performer (with the passage un blocked & no spacer) and do not have your problem. It sounds more like a carburetor that needs re building or replacement.
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