01 malibu mutiple missfie

well here I go again. this is the same Malibu I worked on a year ago.
here is what is happening and what I have done so far.
it is miss firing and is hard to start. have to give it throttle to get it to start. codes read misfire. p0300 and then for specific cylinders.
so I have replaced plugs and wires. still acting up. changed back to old coil pack assembly. it was worse. ended up with egr insufficient flow code and catylist code. she then had cat replaced. then still had miss fire. still hard to start. so she took to person the cat he read real time codes and test and said 2 of the coils are the problem. replace them. still not right. replaced ignition module, and still not right.
oh, when I replaced module, I disconnected battery, and when I put new one on, then reconnected battery, it started turning over the engine. took terminal off battery and tried again, and did not try to start then, and still hard to start, and still have multiple cyclinder misfire.
so, could this be that the ECM needs to be reflashed, or should I just tell the girl to set it on fire?
and also she got a recall on the ignition switch also.
I think she should have had a dealer put it on a computer to see if they could have found something.

the car just does not want to run. it is constantly quit running. getting harder to start.
any help would be appreciated.

Injectors could be dirty.

Lot of parts, no results......called guessing and shot gunning parts......not diagnosis...

so when you connected the battery back the engine started to turn over ? was the key in the ignition ? if it was you may have fried your PCM (car computer)