crazy idle

when my car is idling itll rev up to about 1500 then drop to 1000 or so and itll do this over and over and over really annoying and one of my friends said its nothing to worry about as long as it starts fine and doesnt die but my last MX3 did and i was wondering if anyone else had the problem and knows how to fix it cause its driving me insane

make sure you have no vaccum leaks. and also makes sure your VAF is plugged properly.

get your o2 sensors checked out