OK, so i'm working on my sisters car 2002 eclipse 2.4L . I have basically no experience working on Mitsubishi motors so I dont know their weak points, and little headache causing bits. Background: I've changed timing belts and headgaskets before and I am a mechanic, just not working on cars.

So here goes: We changed the headgasket (used new bolts), waterpump, timing belt, balance shaft belt, tensioners, oil, coolant, plugs, and plug boots. Started it up, figured we missing hooking up IAT, well i think it was IAT, its a small sensor on the back bottom of the intake. After figuring that out, it seemed to run fine, smooth, idled ok, revved up ok, no weird noises. I warmed it up checked coolant, ran the heater, made sure coolant level was right checked it over some more. Ran the AC, put it in drive, reverse, listened for noises... All seemed fine.

Pulled it out of the garage, put it in park and it died. Now it will start fine, and run ok, as long as i dont let it idle, it dies at idle every time. I know it has a bad O2 sensor, but I really doubt its causing this issue. I had to leave for work, so I havnt pulled the codes yet.

I have 2 connector leads (both female) from the harness that are short and right under the throttle body that arent connected to anything, I cant find anything to connect them to. I assume they are extra connectors for options her car doesnt have but can anyone confirm this?

In the past her car has had a somewhat similar issue, her battery cables were completely corroded and the car would die at idle. It looks like water must just run right across the battery? The wires were replaced, now they are corroded again but not terribly bad. Car starts fast and voltage to the battery seems good, engine ground wire is properly attached.

I'll pull the codes when I get home, but as of right now i'm kinda clueless. Timing marks were dead on when we put it back together and it was running great in the garage for at least 30min before we pulled it out? Also checked the oil, and coolant, no visible signs of mixing. Temp was sitting right below 1/2 point on the gauge.

If you have any ideas it would really help.
Thanks
Paul

whenever you disconnect the battery, you need to let it idle for about 10 minutes to relearn the idle. Don't touch anything unless you have to rev it to keep it running. If that doesn't fix it, then clean out your MAS.