1990 yamaha 50hp 2stroke throttle problem

The other day on lake erie my motor started to act up. As I would accelerate the.motor would try to cut out once I hit about 20mph. I would have to put the control back into neutral and try again to try to fix the problem. This worked less than half the time. My dad went in the back and took the cal off and he could manually.move the throttle with no problems and I had to steer from the console.. throttle cable bad? Sparks? There is no hesitation in the motor when my dad does it manually from the engine. Only when I try to do it with my controls.. thanks for any help, Ed

With the cowling off the engine and the engine shut off, have some observe the throttlw linkage in the engine as you advance the throttle. If I were to guess the throttle cable/linkage has come lose somewhere in there. You advance the throttle and the cable is moving lose in the engine 1/2 way with the linkage opening the throttle only 1/2 way. As you move back to neutral, the linkage closes the throttle 1/2 way and the cable moves the other 1/2 way. The throttle cable should be fastened to a fixed point somewhere such that when the throttle is advanced, there is no movement of the cable.. only the linkage that is attached to the throttle.