89 30hp evinrude not running quite right

I recently bought a 16ft jon boat with an 89 30hp evinrude tiller on the back. The motor runs and starts with no problems until i run it at WOT. It'll run at WOT for about five minutes then it will stall and try to get back to WOT rpms but never does, it revs up then drops to idle rpms then revs back up repeatedly. Immediately after this happens I turn the motor off, let it sit a minute and start it up again and it runs fine except at WOT. I'm somewhat familiar with small engines but not so much with outboards. It sounds to me like a jet being clogged and causing it not to get fuel. When i bought it the owner put a brand new prop on. It's a 10x15. From what i've read, the prop size can have huge influence on how the motor runs. This is where my knowledge is limited. Any help would be greatly appreciated! thanks

Re: 89 30hp evinrude not running quite right

Sounds more like a fuel supply problem.
Try squeezing the fuel bulb. If that helps, check/replace o-rings in quick connectors (air leak), gasket under fuel-pump top (air leak). It might even be fuel tank vent or fuel pump itself.