having problems with old merc I recently bought on an older bass boat, I had marina go thru entire motor and controls, 1969 100 hp tower of power runs good at idle speed once started, pushing throttle down to speed up causes it to die. local shop did out of water testing only, no testing in water was done. 1st time out on water, throttled up and ran good for 1-2 miles, then when throttled back down to stop, when took off again it would never get back up on plane and now dies out when give it throttle past very slow idle speeds. throttle is hard to push and operate. can't find anything on web about throttle mechanism, probably too old of a model. the electronic button had to be replaced but now the choke seems to work fine (clicks back on motor when pushing), gas ball and gas line were replaced. seems like not getting enough gas and just dies when giving throttle? any help appreciated!