Help oil light is alive

Hey guys, I have a bmw e46 318I n42. Recently changed my oil pump and now the oil light stays in while it idles and when I rev the car over 1 the light goes off. I also feel like the idle is too low. Im not sure what could be the issue. I did decat the car last year some time. I have had no luck trying to diagnose the car and tired of being ripped off by so called bmw mechanics