04 impala loping /hunting idle ?

My mom has an 04 impala 3.8 vs . When you first start it up every morning it revs by it self, kinda like loping idle or hunting how ever you want to say it . I’ve ran a scanner to it and i forgot what it showed . I’ll scan it again when I have time but you can mash the throttle and it’ll stop but it won’t do it anymore until it’s under operating temperature . Me guessing sounds like a map sensor . What do you all think . I’ll try and get a video of it doing it .