Hi I have a 2002 4runner and I was wondering when do you change the spark plugson it? I take it to the dealer for tune ups and they keep telling me at 20 then another time at 30, and now they say at 60,000 and I am at 41,000 now. I amwondering if this could be my clicking noise in engine some times. THanks in advance

 

I doubt they are the source of your clicking noise, but I would change them.
I do mine every 30 to 40K just to stay in top shape.
There is definately some wear on them at that age altough they will technically run for much longer.

 

I do mines every 25K which means it`s time for my second change. Drivers side is easy, passeger side requires a bit more work. As stated above, that is not the source of you clicking sound. Explain more in detail and we may be able to help you.