This is caused by a poor oiling design inherent in the overhead valve train components. Most of us don't see this in normal use, but you will see exactly what you are describing as a result of improper oiling during high speed turns. I have more info here on my web site, as well as a mod you can make to the rockers to eliminate this problem:
Rocker Arm Oiling Info

It sucks, but it speaks to the forklift roots of this motor: it was never designed with extended high speed cornering in mind.

Good luck,

-Jeff

Jeff Moskovitz
1986 turbo 4X4 truck
1998 2.7L/M5 4X4 4Runner

Jeff's 22R-TE page

22RTE Turbo Truck Forum (advertising free)