Checking EGR System

SYMPTOM
* CHECKING EGR SYSTEM

POSSIBLE CAUSES
- Vacuum line to EGR solenoid restriction or leak
- Vacuum nipple at throttle body plugged
- EGR valve assembly engine speed stayed same
- EGR valve assembly tone changed
- EGR valve assembly vacuum <= 3"
- EGR valve assy does not hold vacuum for 30 sec