Slow accelerator Response

Been doing a little work on my new 328GTS to get familiar with her and have noticed that there is hesitation when sitting in neutral and giving a little throttle. Also the throttle returns to a higher (1500rpm) idle sometimes. The plugs are new as of yesterday. I expect dirty injectors and have received new ones but I’m awaiting some other parts before I proceed. Am I correct in my theory or could there be other possible causes?