2001 Mitsubishi Mirage misfire

I was driving my 1.5 mirage when it started to loose power the check eng light was on when we bought it and the car still ran great but after the loss of power we were told cyl 4 had a bad inj we replaced that and the dist as requested by the tech but the car still had a misfire but now in cyl 3 we replaced the wires cap rotor and plugs still a misfire in cyl 3 the tech took a cyl check ,fuel pump press check and checked the engine light which was a evap code i dont know what to do the timing belt water pump and tensioner were just done and the car has been maint very well do you have any ideas