Need help identify problem

I have a ~1972 Mercury Thunderbolt 1150, 110hp enginew and my throttle control is a MerControl. My issue is that the butterflys on my carb are closed when it is in neutral and forward, but open all the way up when in reverse. After the butterfly is open, the only way to lose it is to move the throttle advance all the way forward and then back.

This also has the effect of making it impossible to start unless I put the throttle in reverse a little, then go back to neutral and move the throttle advance all the way forward AND if I go in reverse too far before starting the engine takes off and red-lines until I shut it off... very quickly.

Please let me know if anyone has any ideas...at this point I think the problem is with the throttle control unit, and not the engine.

Just my 2 cents, but perhaps your linkage "slipped" and needs to be readjusted. I had this same issue happen in a 70hp once. I followed the linkage adjustment procedure in the manual and that was the fix.

Are the control cables reversed at the motor ?---------Shift cable installed on the throttle ?

I opened up the throttle control box today. Cables are connected correctly, but I think that the cap that holds the throttle cable was slipping. When I re-assembled it this particular problem was fixed. Thanks for suggesting to check the cables, it helped...now I have another problem which I'll post a new thread.