Q: Not starting MAP/MAF

I had trouble starting me car last week. The first couple of tries it would turn over but not start. Then after several times it finally started and idled at 1000 rpms. The check engine light came on. I turned off the car and tried starting it again, and it started after a few tries. I drove to the repair shop and they checked the ob2 and got these codes: map/maf and glow plug in 3 cylinders. Then I went to another repair shop and asked my friend what the codes meant. He said it meant that everything was wrong. So I bought a new fuel filter. My car started right up with no check engine light. It ran perfect. Then I went to the store to get something for dinner came back out and my car wouldn’t start right away then after a few times it did with no check engine light. When I got home I changed the fuel filter, bled the filter and tried starting it. My battery was dead, so I bought a new battery, installed it, and the car wouldn’t start. I entered the code for alarm, tried starting it, but didn’t start. When I turned the key I could hear the fuel pump working. I left the key on and loosened the top of the fuel filter, and there was fuel coming out of it. I closed it and tried to start it. Do you know what’s wrong and how I can fix my car?