i have an 87 19' with an omc 3.0. the engine & drive run fine. however when i reach planing speed & trim the lower unit up i am hearing a whining/ growling noise coming from the lower unit. when i trim it back down the noise goes away. i'm not trimming it up too far so that's not it. i changed the gimbal bearing yr. before last, so i don't suspect the bearing. i had the drive off this spring for maint. & the u joints were ok. also the boat does not reach the speeds that it once did. at 4000 rpm it will reach 30mph. with 3 on board, so i don't think weight of passengers is the problem. it doesn't need a tune up. i changed plugs, points etc. etc. last season. any ideas? thanx.