I have a 1997 Mercury 75 hp on my 1997 Nitro 700LX. Motor seems extremely cold collared, have to hit the key several times to keep running & then have to quickly put in gear. I have put new bulb, fuel line & fuel filter on it this spring, but today after going thru process & putting in gear it bogged down, would not go on plane. Did this a couple of times & finally when put in gear it took off & never had another problem all day, ran like a top. What could be the problem? Thanks.