New to the group and kind of new to the boating world. I bought 96 silverton at the end of last year. I have been going thru engines and doing all maintenance and repairs myself. We went out sat and in way back port side motor was bogging down at high rpm. I replaced all fuel filters last night and yes they were in bad shape. When I fired up motors I noticed one riser on port motor was extremely hot. I pulled off riser and checked for blockage . Seems as tho water is running thru just fine. What would my next step be to look at.!? Raw water I changed impellars I did clean out oil coolers they did have some old broken of pieces of impellar inside. Boat never over heated on our trip out . Any suggestions bwould be appreciated. Thanks