2005 Mitsubishi Endeavor Third Cylinder Misfire

Hi joshuafm and TY for the donation

Costs of repairs on parts/labor varies with location

A misfire on a specific cylinder should prompt you to check sparkplug, compression and injector for that cylinder in your case cylinder no.3 other additional causes on misfires

Engine misfiring can be caused by the following worn or fouled spark plugs, a weak spark (weak coil, bad spark plug wire), loss of compression, vacuum leaks, anything that causes an unusually lean fuel mixture (lean misfire), an EGR valve that is stuck open, dirty fuel injectors, low fuel pressure, or even bad fuel.