1995 mercury 200xri efi not wanting to get on plane

[Nc bass fishing]

I have a 1995 mercury 200 xri efi that doesn't want to get on plane when first getting to the lake. It will only go about 7mph but after awhile will all of a sudden get on plane and run 60mph and run fine rest of day does idle rough sometimes any idea where to start to resolve the problem

 

[Nc bass fishing]

I forgot to mention that the oil system has been removed and mix oil and gas at 50:1. It was removed before I owned it

 

[Faztbullet]

Several things...stator,switchbox,rect/reg or fuel issues. First step is to check spark on both banks of cylinders when its acting up.

 

[Nc bass fishing]

Several things...stator,switchbox,rect/reg or fuel issues. First step is to check spark on both banks of cylinders when its acting up.

Ok will try to check spark on both banks when acts up but only notice on water but will go and test as much as possible when I get off work to see if I can find anything that might narrow down the search

 

[Faztbullet]

Leave it on trailer for testing