Sounds like it could be a number of things. Maybe even as simple as worn or incorrect spark plugs. i recommend Bosch F8DC4 plugs gapped to .032" or .8mm. Someplace simple to start. How many miles on it, and when was the last major service done ie. air filter, fuel filter, plugs, etc? Fuel filter or fuel quality/octane could be a source also. How about the coolant temp sensor, that may cause this as well, or possibly the intake air temp sensor. Overvolt protection relay, as has been mentioned.....ah, maybe, I'd look at a few basics first. If someone has put in any "fancy" spark plugs such as Platinum tip or "splitfire" or some such plug, that may be a problem.
On the fan, I'm curious why he wants to take it off, but to answer the question, the bolt is a normal "right hand" thread, righty tighty, lefty loosey, and there is a special tool you use to hold the fan hub locked to be able to loosen the bolt, and yes, if you don't know what you're doing with it and force something, things will break.
Take care and welcome to the site.