1974 evinrude triumph 70hp running odd

So its been about a month since I got the motor back from repairs. Carbs rebuilt, new spark plugs, link and sync done, new impeller, new fuel line, new bulb and fuel tank. So for some reason now the boat will start fine and run fine then it just begins to rev up and down on its own for no reason. Does it at wide open throttle but sometimes it will stop if u bsck the throttle off slowly, sometimes it dont. I blend my fuel oil mix dead on and I always run stabil. I may also mention that it does not have this problem at first. Runs great but after about 20 mins or so it starts.cannot figure this out. Any help would be appreciated. Thanks brandon

Does it rev up too high? Sounds like the prop hub may have spun.
Mark it with a permanent marker. Check it once the issue happens again.

Actually no it doesnt rev any high than what its like at full throttle. Basically just up and down up and down. Never dies on me when it starts doing it. If it is the prop causing this how do I go about fixing this? Where and how should I mark it?

This may very difficult to troubleshoot without taking tools out on the water. Test spark right after it starts to happen.
FWIW, I have a 73' 65HP. Two years ago I noticed the stator literally melting. There were no symptoms, just epoxy drips on the block. Look up under the flywheel. Are the coils of the stator showing teardrops?
Are the ignition coils original?
I assume you didn't do the other work yourself?

I will check it a little better this afternoon. But I do know what your talking about with the epoxy drips. The mechanic that did the work told me I was using the wring group size battery battery and it was getting the stator hot. As far as everything else im sure its all original. One thing I did notice is my primer bulb was losing prime. Went through and found some small leaks and re tightened some clamps and now my bulb is holding prime very well. Dont know if that may have been a problem. Any more suggestions would be much appreciated! Got to get this fixed