1992 Toyota Cressida running rough / stalls - 150,000 miles

I recently made the mistake of leaving my car sitting outside while on vacation for 2 weeks. I live in Dallas and I think the weather while I was gone got as cold as between 35F and 47F at night - not sure if the cold-ish weather would have anything to do with my problem. When I came back and tried to start the car, it wouldn't start. The engine was having a really rough time turning over, but I could hear the starter motor working (along with my radio) so I assume that the battery/charging system and starter motor are all fine.

Eventually, I was able to get the car to run but very roughly. This required me to press down on the accelerator quite a bit. It sounded like it was turning over more smoothly when I got the rpms up to over 3000 or so. When I tried to let it idle, the engine would simply stall. I've been trying to start this vehicle periodically over the last three days, and it seems to be getting a little better as time passes. Now, it may idle (and not stall) at just under 1000 RPMs but still does so roughly. I haven't tried to drive anywhere for fear of the car stalling in the middle of the road.

Do you have any ideas of what could be causing these problems after the car has been sitting idle for 2 weeks. Prior to this, it was running fine for its age. Thanks.