I purchased a Tohatsu 6hp 4 stroke engine a year ago and though it has run dependably it has had idle issues almost since day one. This makes changing gear and maneuvering in slow speed situations difficult. This common issue is caused by extremely tight tolerances in engine design forced upon it by EPA regulations (which were created based on false information). Ethanol added to fuel compounds the problem and again is a result of EPA regulations. So what to do? First off cleaning the Carburetor is step one, making sure you run the fuel out after each running and using additives to prevent water build up and to keep the fuel fresh will help prevent this issue. I did all this to no avail, after much research I found a mechanic who recommended drilling out the welch plug that covers a fuel/air adjustment valve. At first I was apprehensive not knowing exactly what this did and even where it was. I finally was able to identify this plug and realized it's only purpose was to prevent access to the valve. I decided to give it a try and low and behold it worked. While this will no doubt VOID YOUR WARRANTY it can't hurt in fact you can always order the plug and replace it as no damage is done. A small drill bit will take care of the plug and you can adjust away. Mine ran better just removing the plug, perhaps the bit touched the adjustment screw. Be careful to clean up the loose bits of brass before firing the engine up. I am guessing this will help when doing a carburetor cleaning as well as this valve can be removed giving access for the cleaner to clear this port out.