Please help.

ok I have a 1989 chevy cavlier 2.0. i start it and it idles perfectly. When i give it gas it dogs out. I has a brand new fuel pump and filter. have replaced the map sensor, the air temp sensor, as a new o2 sensor. when we decided to replace the map sensor we unplugged the old one and it started running when we gave it gas it did not dog out. when we tried to drive it, it drove fine then started not staying running. Please if any one can help with this problem it will be appreciated.