2003 Buick Century Car Intermittently Won T Idle Down Times Runs 65 Mph Without

2003 BUICK CENTURY
200,000 MILES
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Car intermittently won't idle down. at times runs 65 mph without
foot on gas pedal.

I have had the transmission checked (nothing wrong); disconnected the Cruise control, the only code display is PO446 Evap Control system which has been showing for 2 years. We replaced every sensor, took the Evap canister down, even replaced gas cap, nothing cured it. so I just drove it with engine light on. What is the problem?
Mar 28, 2013 at 6:42 AM
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JDL
  • ✓Experienced Mechanic
  • 16,098 POSTS
Block off the mouth of throttle body, see if it has any effect on the idle? It should kill the engine. If no effect on idle, look for a vacuum leak.
Mar 28, 2013 at 1:12 PM
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