Ulysses Calles

So heres my story my catalytic converter (cal emission) went out and also my fuel pump went out with it so I gutted my cat and replaced the fuel pump and now my 2008 lancer gts starts in the morning and then I let it you know warm up and it seems to be ok stay on but revolutions stay at 2k idk why and once I tujr it off and try starting the vehicle again it just cranks and stays off until the next it day it would start if you guys can help much would be appreciated I believe it could be something with fuel such as fuel injectors what do you guys think??