1985 75 hp 4 cly. mercury outboard start and run in neutral will not run in gear. I bought this boat last fall picked it up at marine mechanic shop said he rebuilt carbs. and it ran fine. Put it in the water and the motor starts and idles will accelerate in neutral but dies like the power is shut off when putting it in gear. Tried to put jerk it in gear but it dies like neutral switch is killing it. Is it possible do they have something in the wiring that will do that?