I have a 1984 Johnson 150GT. It has a recent complete overhaul and usually starts fine and runs great. Problem is when I get ready to put it back on the trailer. First I tilt the engine forward a little to make sure it doesn't hit the ramp then gas it to load on the trailer. The minute the boat angles up a bit to go on the trailer the engine dies. I restart the engine and it won't throttle up at all after that. Any ideas?