Where to start...I have a 1990 Bayliner Cierra 2651 with a 5.7 Mercruiser and Alpha one outdrive. Boat ran great when I first bought it last year until I snagged a rope at cruise speed. Shortly after I lost all drive. I cracked open the outdrive to find the upper end gears mashed. I brought the outdrive to a boat shop in Maine and had it rebuilt...$1400 later I picked up my outdrive and was very surprised to see the old ujoints still on it. Reinstalled the outdrive and that lasted about 5 trips. Was cruising one day and lost all thrust, overheated...as long as I kept the rpm's under 800 it brought me back to port. Called a local boat shop they told me it had to be the coupler. I pulled the boat out last September and about a month ago I pulled the outdrive off and pulled the motor out, changed the coupler(old one didn't look that bad), changed oil, filters, plugs, thermostat, gimball, bellows...did everything I figured I needed to do. Put the boat back out...noticed a noise in the back and a vibration...pushed the throttle ahead and (*!(*W^(@*&!^*&%^*&#@) it lost all thrust AGAIN!!! Put the boat back on the trailer and went home...after reading some posts on here I went out, put the boat in drive, went out behind and yep...A year befor I had simply spun the hub in my prop! Went and got a new prop...put it on...put the boat back in the water and voila....THRUST!!! After about 5 mins at cruising speed...my temp crept up to 200 and over.....limped back to my berth and went home. Went out today and changed the impeller in the water pump...cools alright now at cruising speed but the heat creeps up at idle...hmmmm? If I rev at around 700 to 800 it cools fine but at idle...500rpm it heats up. And by the way that vibration and noise is still there which concerns me...the coupler is new, the gimball bearing is new, the prop is new, the impeller is new, the engine alignment tool was used...any ideas on the vibration? Also when I took the lower off today I noticed my drive oil is GRAY...Seems like it's one problem after another...any ideas?