The intake manifolds have rubber sections but the carb bolts flat against the back of the engine housing and wouldn't move much when removing the mounting screws... but I did get a thin layer of mica between. I've also increased air flow into the cowl and provided a baffle director to direct the air flow up to the carb area which sets behind the engine.
The problem didn't exist when the cowl was not installed and showed up on the second flight after it was installed. The first flight was ten minutes and it manifested about 4-5 min into the second flight but once it started, it grew increasingly worse so the plane was brought in for a landing and died shortly before touch down. It would not restart... until cooling. the jugs extend beyond the cowl so they are not heating excessively.
I will try to fly this afternoon and test the changes.