Yup, sounds like exact same problem. If you turn on the system you can hear the leak at the pressure switch. Is your bowl holding water? If it is that’s your problem. The switch. Part around $200
I just finished changing out duckbills (all 4) and still had a vacuum leak. After further research it was the pressure switch that failed and was leaking through small pinhole. I Listened for air, and found the leak at the base of pressure switch. The duckbills were worn as well. Nasty job but...
I have 04 390 w reg 8.1s def not under powered and if complaining about gas why have a boat. I will say anything bigger diesel would be the way I’d go. Overall we get a ton of smiles, attention and likes. Sexy boat!