Would be noce to know year and other pertinent information - based on trouble codes, I will assume you have something built between 1989 and 1995
332- insufficient egr flow detected - your egr system measures pressure differential across the valve to give indication if it is working or not. Wither a bad EGR valve, a bad solenoid which operates the valve actuator. a bad diaphram in the vacuum actuator for the valve, or clogged ports at either the exhaust inlet or egr valve outlet at the intake manifold. Fortunately, your Haynes or Chiltons will give you the exact diagnostic procedures for this specific car.
411-cannot control rpm during koer low rpm
538-insufficient rpm change during koer dynamic response test invalid cylinder balance test due to throttle movement during test
Both 411 and 538 indicate there is an issue with the idle control circuit or an issue with the TPS or the throttle body its self.
536-brake on-off switch or boo circuit not activated during koer - the test procedures for KOER test require pressing the brake pedal during the test - this was not done and should not indicate a problem
521-power steering pressure switch circuit fault - the power steering system has a pressure switch to tell the ECM you are steering the car and to adjust idle to compensate (makes sure power steering pump has enough power to drive it while doing low rpm operations such as parking - could be bad pressure switch or short or open in wiring between switch and ECM
Check fuses and make sure some control circuit fuse has not blown - this often causes multiple trouble codes.