Motor: Yamaha 50TLR 2-stroke Prop: Powertech SCB3 15pitch Extra info: Motor is in second mounting hole. Motor does this trimmed all the way down, and also keeps doing it with the trim bumped up slightly. I also have a 14pitch prop being sent to me by PT this week. Edit to add: PT is sending me the new prop because Ken @ propgods said the 14p will put me around 5300-5400RPM WOT instead of the 5100 I am at now. When running the skiff with two or three people and a normal load, I will get on plane and yadda yadda and keep the throttle at 3/4 for cruising. This puts the RPM around 4200-4600RPM (5100RPM is WOT with this prop). While running, the boat will suddenly lose speed and the tach will read 4000RPM. I can lay the throttle down all the way to WOT and it wont budge, but sometimes it will. Other times, I have to back off the throttle and then gun it again to get over 4000RPM. I'm thinking this is a cavitation/slipping issue of the prop? Could it be the powerpack going bad? Bad spark plug?