Power Steering like all other accessories tax the 'power' of the engine; if there is a problem in the power steering causing excessive load on the engine it will loose power (more so in low horsepower engines).
At the front of the engine , towards the drivers side of the engine ( power steering fluid reservoir on a 1998 Mercury Grand Marquis )
At the power steering pump reservoir. The power steering pump or reservoir is located on the left side of the engine between the engine and the firewall
could be where your power steering fluid is cold and thick
check your power steering pump might be going out or might be low of power steering fluid
Top middle of engine.
If a car engine stalls when turning, there could be a problem with the power steering pump. There could also be an issue with an emissions control device.
With the engine off, remove the power steering reservoir cap, and read the fluid level.
check power steering fluid and check to see if battery is good
I was looking at a picture in the 2003 Mercury Grand Marquis Owner Guide and it shows the power steering fluid reservoir at the front of the engine compartment between the engine coolant reservoir and the engine air filter box
problem with power steering 1994 Pontiac grand am 2.3L
where is the power steering reservoir on a 2006 grand prix
A bad alternator. Turning the steering wheel all the way is very demanding on the power steering which draws power from the engine and can cause the idle to dip down. A weak alternator is usually the cause for the stalling.