Mercury classic 50, 45 power trim issue

[Iwanttofish]

I have a mercury classic 50 45 power trim on an 1987 bass tracker tournament v-17. My father and I have a big fishing trip coming up to the st Lawrence river and instead of renting a boat this year he decided to purchase one for us to use. The issue I’m having is the motor starts at full throttle and I can bring throttle back halfway and it runs great. From half throttle to idle it starts bogging down and at idle it pretty much dies other than a couple times we managed to have it run in idle beautifully for maybe 45 seconds. We replaced a gasket on the upper carb where it was leaking fuel and fixed that issue but have no clue what to do next.

 

[racerone]

Step #1 is a new impeller on a " new to you motor"--------First test compression and post numbers.---Check for spark on each lead.-----If all good then open low speed mixture screw 1/8 turn at a time and test run.----Test run with boat floating in the river or lake.