I’ve had my 1980 for alittle over a year. Last year it seemed to run fine and get pretty good speeds, atleast around what I was expecting, mid 50s. After I took it out of winter storage and ran it for the first time this year it seems much slower. I live on a river with a lot of current, and when I’m running up River I can get maybe 47-49 if I’m lucky, and going down river only getting maybe 53 if I’m lucky. I played with the manual jack plate a bit and lowered it some because it seemed like I needed to be able to trim up more, and that seemed to help alittle, but I want to start fresh at a certain prop to pad height and adjust it correctly so I can get the most out of the boat and motor. It’s a Mercury 150 four stroke and a 6” manual slide master jack plate. I see other people getting close to 60 mph out of their boat, same setup, so something isn’t set up quite right on mine. I also added power poles this year, but noticed the loss of speed before I added them. Any help will be greatly appreciated.