1999 Rude with oil problem

I'm a new member, as I've just found this site and seems to be very informative. As the title says I have a '99 Rude which has been running great, but we were on the lake the other day and after running it for a mile or so wide open I came to a no wake zone and pulled it back to idle, when I did I got a no oil alarm. After checking it out I believe that it is oiling since it has oil in the throats. I removed the oil pressure switch and put a gauge in and the needle was fluctuating madly, but appeared to be in the range of 3 to 9 lbs. Is it normal for a gauge to fluctuate like this and do you think that I am right in thinking that is the pressure switch, if not what else could it be? Thanks for any help that you can give me. Gary

Please repost with your model and serial #'s It will help the guys to determine which engine they are dealing with.

Its gonna pulse like that because the lift pump you installed it in is a pulse pump (lift pump). Check the pressure switch with an ohmmeter. You'll see it open and close as you add pressure to the threaded port (with a mityvac or equivalent). Im guessing not likely the pressure switch but more likely a faulty lift pump itself, pressure switch within the injector, or an open wire between the injector and emm