im wondering if the cooling fans clutch on my 97 4runner v6 is shot, or its something else wrong. my friends dad is a mechanic, and he said its the fans clutch, but im jus wondering if any of you had this same problem.

recently (not at any specific time) the throttle response and power of the engine has been less than par. its really noticeable, and the engine gets really loud, like makes a whooshing sound an stuff...friends dad says the fan clutch is supposed to only make the fan turn when at low speed or idling when theres little air flow to the radiator, but its probably messed so it engages at weird times now...so if i floor it, the fan is engaged and takes a lot of power from the engine. is this true? if so, how much would this cost to fix?