Toyota Repair: Vacuum sucking power steering fluid into engine, power steering fluid, low speed

Question
How do I locate the problem?  Original 1991 4-runner engine replaced with 1994 4-runner engine.
Now the power steering fluid is being sucked into the engine.  The 4-runner has ABS.

Answer
There is a valve in the top of the power steering pump. It detects extra load from low speed turning and raises the engine idle. The only way I know to get PS fluid into the engine would be if that valve was cracked and allowed fluid up the hose into the intake.
Mike