You're showing 15 psi difference between the lowest and highest compression reading. If you're not checking the compression yourself, buy a gauge (gauges
The hose pressure must be turned on full blast for that high hp engine. Was it?
(Testing Tachometer With Water Cooled Regulator/Rectifier)
A quick check is to simply plug in a another new tachometer
You did not say if it only idles or if it will run at higher speeds.
Need to isolate problem to fuel, spark, or overheat.
The alcohol in the fuel absorbs the water as it condenses if you leave the vent open the rise and fall of the barometer causes the tank to breath and