My number 6 cylinder seems to be weak. I bought the 4runner at Christmas and it has a miss. When I unplug #6 sparkplug wire the miss is still there. I have been reading that that valve may burn because of the exhaust pipe. Has the 3.0 ever been known to break a spring?

 

I doubt that it would be a broken spring. Most likey is a burnt valve, happens all the time on #6 in the 3.0.

 

I've never heard of a spring breaking on one. Probably a burnt valve or a HG leak. Do a compression test.