There is nothing wrong with the 3.0 per say.  It is more like there isn't much right about it. 
 

This pretty much sums it up.  They're overweight, underpowered, had some head problems,and are one of toyota's if not toyota's worst motor.  However, seeing as toyota's worst motor still gets 200-300K before dropping dead is a testament to toyota quality.  I've gone through 3 motors in 2 years, I'm still on the third, and its got 220K on it now.  Other two crapped out at about 185K (cracked block on #1, blown heads on #2) 

They are a PITA to work on, but I've got a 3: body lift, so that really helps.  Not sure if I could work on it without it.  My g/f's brother has the same truck but w/o the body lift, and when he did his heads, it took some creative positioning to get everything back in.


I've discovered that headwise, they're easier to replace than to do the heads