Check out this article with 12 tips when servicing brakes & how it effects steering.
Vehicles with power steering pump-powered hydroboost brake systems.
Pedal kickback, grabbing brakes, increased pedal effort, hissing noise while applying brakes or increased steering effort.
Possible contamination of hydroboost system due to deteriorating hoses, contaminated fluid or steering unit failure.
It may be possible to restore proper operation by flushing the system using the following procedure. An in-line filter MUST be used during the cleaning cycle. After cleaning, if the filter and fluid show obvious signs of hose contamination, all hoses must be replaced and both fluid and the in-line filter changed again.”