[schoward]

The rev limiter can simply be unplugged to disable it and see if that is your issue. The car will run just fine with it unplugged as it is not needed to provide power to the fuel pump. It's only function is to interrupt power once 7000 Rpms is hit.

It is the square box on the side bulkhead behind the fuel gauge with an 'x' on it and is easily accessible from the frunk simply reach in and unplug it and see if problem goes away. It is a super easy test and takes 30 seconds.

I have had two of these boxes go bad and cause power issues to the fuel pump. My original went awry and then a used one from parts heaven lasted 10 years and then went on the fritz. In both cases the car would run but would flicker power to fuel pump just enough to cause the car to run slightly 'off'. Both times (on both boxes). unplugging the box corrected the issue proving it was the relay box. When the first one went bad, the fuel pump would run but intermittent power made it sound like gravel was going through it. On the second one the car just ran a little bit off and seem to buck a little bit under light throttle but still ran and drove.

Easy test - reach in from frunk and unplug the rectangular white plug front the bottom and see if any change. There is no adverse effect you just won't have rev limiter while unplugged.