I have a 1996 60 hp mariner on a fisher pontoon.I am getting water in the cowling some how.The cover is good and tight.I've looked while someone else drove with cover off and don't see where its coming from,but not at w.o.t.After about 1 hour of cruising it gets enough in bottom cowling to make it start dieing down to about 3000 rpm.It is not coming out of telltale hose.It is causing other problems too I think.Sometimes the power trim works by itself & the tach stops working for short periods.Please advise