2001 Galant Starting Problems

This is what I have a Mitsubishi Gallant LS 2001 engine code (G672) SOHC 3.0 LITER.

The problem I sold this car to my ex-girlfriend (definitely problem # 1) anyhow the car was fine when I owned it and about two month after she had the car it stared acting a little funny. The car has a hard time starting, so I ran it through some codes and found nothing. So the other day it just would not start. So we checked the basics cable, battery, starter, alternator, everything was fine. Well it happened again so we ran another test on everything came back the battery was no good. Install that few days later (same problem) this time ran a test alternator bad changed that and damn the luck (same problem) now its at the dealer and they can not find any problems (imagine that) The car starts fine and runs but as soon as you get to far from home the damn thing is just dead when you go to start it. Has anyone had any problem like this, my ex is driving me crazy (like this is my problem) someone told me maybe the ignition switch is bad? Any thoughts on this would be greatly appreciated. Thanks - Jason