This is starting to happen in mine and it has almost 103000 miles. My dad had a truck a while back with the 3.0 and it started the same noise at around 110000. we took it to toyota where a good friend is the head mechanic and he said that the valves are a little loose. He said that they are better loose than tight and not to worry about it. I have heard many other 3.0 do the same thing. Just my .02