What would cause a car to idle heavily?

check your EGR valve for leaks on your exhaust manifold

Answer

Check your Air filter or Fuel filter. I replace my air filter once a year, Maybe replace your Fuel filter after 30,000 miles.

A high idle is typical of a vacuum leak, I don't know where the above answer has any relation to this.

if you have a carb, it may not be adjusted correctly..

First answer by James. Last edit by Lbeckman. Contributor trust: 81 [recommend contributor]. Question popularity: 190 [recommend question]

Research your answer:

Our contributors said this page should be displayed for the questions below. (Where do these come from

)

If any of these are not a genuine rephrasing of the question, please help out and edit these alternates.

Reasons cars may idle heavily?