1998 Pontiac Firefly Rough start and stalls when put into d

My 1998 Firefly (with 120,000 km on it) wouldn't start this morning. It took multiple trys to get the engine to catch. It was turning over, but sounded rough, like it wasn't getting gas to it properly. When it did start up finally it sounded fine, and all electrical was working. When I put it in drive it stalled right away. After that it took a lot more tries to get it started again, and when I turned on the heater fan it stalled out. Attempts after that to get it started failed, and the exhaust started making "popping" sounds when I'd stop trying to get the engine to fire up. It was still turning over, just really rough and chugging sounding. Last time I drove it I took it through a car wash just before I parked it, and it has sat without running for two days in very cool humid weather. Any thoughts?