1988 Mazda 323, power surge at end-stops of steering
 

1988 Mazda 323 with power surge at end-stops of power steering.

Hi, i know that there is a vacuum activated when the steering comes to the left or right 'stops', and that gives more power to the engine to overcome the power the power steering pump takes, but my hatchback's over-power seems to have got a lot stronger. When I steer hard for parking, the engine really surges ahead. It is a bit dangerous! - I do not remember this as a problem until recently. Any ideas on the this?

When I turn the steering fully left or right, I can see a vacuum pot on the left rear (when facing the front of the car) of the engine opens. I wonder if the engine may simply be running too rich and that is why it gets such a boost when the extra air comes in.
Thanks,
MidAtlantian