86 mercruiser alpha one 140 runs well but then doesnt start

I just bought this 86 4 winns 170 it has a alpha one 140 mercruiser motor the boat is in great condition. I took it out it starts and runs great BUT itseems like everytime i back out of the dock and move control lever from reverse to neutral it stalls i generally can get it to start back up and get it to shift into foward fine we run the boat for the next couple of hours not non stop but pulling a tube. when i come back into dock and repeat same procedure it will stall when shifting from reverse to neutral and will not start at all. I replaced rotor, cap, wires and plugs. the boat starts right up but we always have a problem stalling from reverse to forward or neutral. any help would be most appreciated thanks 864winns

probably needs a shift cable....check the shift interrupter switch and see if that's what killing the engine.....when it comes out of gear (either FWD or REV)....