My 2007 Mazda 3 idles roughly intermittently and sometimes almost dies with the aircond. on. Other times it idles smoothly. Any ideas on how to troubleshoot this problem?

 

Start simple and check spark plugs. Also pull off the mass air flow sensor and clean it(it can never be too clean). Check engine light on?

 

Check engine light not on.

 

Also check spark plugs and if u did or are going to replace them don't put cheapies in it the car will run even worse. U dont have to buy the mazda brand because u can get the same ones at an auto parts store just buy ngk's. they are exactly what mazda uses