Hi,<br /><br />A few months ago I bought a 1997 maxum boat with a 120 HP Force by Mercury of the same year. The first few times I took the boat out it run very well with a top speed of 45 miles per hour. Then it happened, it started to loose power and would take off very sluggish. Then it would work fine. For the last 4 or five times that I have taken the boat out, it does not go any faster than 35 M/H with a sluggish take off.<br /><br />I have done the following:<br /><br />Replaced the spark plugs<br />Use hiest oct gas and best oil in the mix<br />Verified that all pistons are firing<br />Verified that all coils are working (to the best of my knowledge)<br /><br />I'm lost to say the least. I don't know what else to do so any help will be greatly appreciated.<br /><br />Thanks. 