87 Merc 45 runs away, solution found

[Flying Scott]

The throttle control was set up backwards, for a Merc Mariner. Handle @ idle, engine full. Handle @ full throttle, engine idles. Throttle control is being changed.
Alan

 

[Chris1956]

Did it have some sort of Johnnyrude throttle on it?

 

[Texasmark]

Well sir, that would certainly play hell with things. Glad you found it.