Hello, I’ve got an ‘87 GN with 28k miles and about 3 months ago it started making a strange sound under boost almost like a goose “honking”. It continues as long as I’m in it. Response is still there from what I can tell and most of the power as I can remember As I don’t drive it a lot. But I’m sure some power is missing as it doesn’t sound good. Not sure what to look for so checking here. TIA