Daughters escape stalled at a light and started knocking once she restarted it and continues to stall at stops if it's warm. The knock is still there 98% of the time and will run until warm but then stall as it approaches idle speed. Once it stalls it's very difficult to turn over (like the battery is almost dead) but once it's cooled it'll start again. We bought it used with 155000 on it and it's never started easily (cranks for a few seconds) to start it. The knock sounds like a lifter and strangely didn't start until after it stalled. I ran it with the valve cover off and all looks well as far as I can tell. I'm totally stumped as it seems it can be so many things. It definitely needs plugs and I tried a new fuel pump driver module (made no difference). I'm thinking fuel pump, IAC, battery, alarm system (I pulled the fuse), ECM, catalytic converter and so on. Any help would be greatly appreciated!