1997 Eagle Talon

I've replaced the IAT sensor, fuel pump, injectors, and spark plugs. I've cleared codes and drove. Came back up this time running ignition code check with codes 12 and 55. My Haynes manual says that 12 stands for power unhooked in the last 50 starts and 55 stands for end of codes.
I have an older Haynes computer codes manuals and it sugjests that it is the air flow problem.
What do you think?
Thanks

Fuel pump runs for a few seconds after turning on key. I wasn't aware, but makes perfect since, fuel pump running while cranking engine. I know on Ford Pickups the fuel pump runs for only a few seconds after turning on ignition. So what causes the pump to run for only a few seconds on this car? The Powertrain box? Or is the fuel pump and/or the MFI relay a timed relay?
I finally got car running great, knock on wood. No more codes with the Genisys tester. Still get codes 12 and 55 with ignition key test.
I changed the fuel filter, fuel pump, injectors, IAT sensor, spark plugs, and lastly plug wires. I feel all was needed except for the fuel pump. I put the fuel pump on a vaccum/pressure tester and it tested OK. I had all ready bought the fuel pump and it was so easy to get to. Oh well, thats a do it your selfer!!! Probably would have spend the same if I toke it to a garage.
Thanks again for the suggestions and help.