After reading TNRabbit's sig link (highly recommend), I just posted with someone who had the same issue. It's common on the 3VZ-E engines, mine did it too but before I did the same "mod".
Here's the post: http://www.yotatech.com/f116/89-pick.../#post52024129
I'm confident it's the same issue but every truck is different so no guarantees. I've had some very unique issues with mine that weren't as easy as it seemed. Just don't buy any sensors until you tested them to make sure they are bad per the instructions in the FSM (using a multi-meter).