2000 ZR2 Flashing SES light, running sluggishly

I only have 30K miles on my 2000 Blazer ZR2. I was really low on gas and parked on a hill. When I started the blazer, it was running sluggishly. The Service Engine Soon light came on and is flashing. I filled the blazer up and took it home. I started it this morning and it was running fine. However, the light came back on after running it for 5 miles. It started running badly again. Almost as if it is only running on 4 cylinders.

I checked the gas cap and it is on tight. Can the gas caps go bad? Could i have a bad O2 sensor? Could the fuel filter be plugged since i was low on fuel and it was parked on a hill?

I would appreciate your help:)

Flashing SES usually means a misfire condition that could damage the catalytic. Replacing the fuel filter is a good idea if it hasn't been done in the past year. You may want to put a new distributor cap and rotor on. Other than those items, I'd have it scanned before replacing anything else