i have 2 '01 quadrunners. the first runs strong but the second takes about 10 seconds to start and once it starts running i have to rev it high with the brake on to get it running. when i let off the throttle it also cuts out and i have to put on the brake and rev it more. i was thinking a carb problem, fuel filter, or spark plugs. what could it be

 

I think you just answered your own question. Get a new fuel filter, drain the tank, change the plug. These are all routine maintenence and are cheap. If that doesn't work pull the carb off and have someone help you clean it that has a clue on what they are doing. Or if you are somewhat m mechanically inclined, and have a manual you can do it yourself.