03 ES Stalling

Hey guys, I know it's been a while. I actually haven't driven the galant in about a year and a half because it keep a stalling when I was driving it if I didn't keep the rpms up. I changed the spark plugs and they had oil in them so I changed the valve cover gasket and the O2 sensor by the cat. I really don't know what's wrong and I've taken it to a couple of guys where one thought it was fixed but only for a little while and the other had no clue and thought it was some kind of electric problem. Again it starts when I charge the battery but stalls soon after. I don't wanna get rid of it but km being forced to. If anyone can help diagnose this, if really appreciate it. Thanks.


JD