18hp Intek on 42" lawnmower starts fine...runs fine under no load, runs decent under load but when mowing and i hit a patch of thick grass, the mower begins to run rough then wont run smooth again till i dis-engage the blades, and let it idle for a minute or so. While running rough it has a strong gas smell. fuel filter ok, air filter ok, fairly new fuel pump, new fuel lines. It seems to me that I'm hsaving am fuel supply problem...am i on the right track??