I posted about this problem last Aug. but since I couldn't find the post to refresh it I will update and ask another question. My 85 force 125 ran great last summer then started alternating between 2500 and 5000 RPM like someone was yanking the throttle back and forth. So I took the advice I received here and last week replaced my fuel lines, cleaned out the tank, etc. So I officially ruled out fuel. Next I bought a spark plug wire tester and compression tester. Compression test results 130,129,130,128. Spark plug wires tester (basically a light that lights up if there is current,i guess) showed strong on top three coils wires and plugs. bottom coil and plug had a flicker of light and the wire itself was dead. So I replaced the coil.It ran good on the muffs so today i took the boat to the lake to test under load and I couldnt get the RPMs past 3000, and the engine died every time i put it in idle. it did lug back and forth alittle but not nearly as bad as last summer. I am pretty sure the engine was only running on three cyl at the most. I am going to guess one of the CDI units is bad, but i dont know if they could cause intermitant firing. I am trying to avoid the repair shop but I am out of ideas, 
<br />Carbs are clean, new plugs, fresh gas, all wires have been checked, throttle linkage is good.Is it possible to test a CDI? or could it the stator? Thank you in advance for the help.
<br />Carbs are clean, new plugs, fresh gas, all wires have been checked, throttle linkage is good.Is it possible to test a CDI? or could it the stator? Thank you in advance for the help.