I started the car today and the RPMS was around 1500 then kinda went down and back up and almost sounded as if the car was going to die...then it dropped to 1K. Today the temp was like 75 with 87% humidity. Once we got to where we was going the car sat for about 1hr and when I started the car it didnt do it. Could it be it "warming up". I never have notice it do that or make that almost stuttering sound. Could it be because I don't have the res. no more and I can hear more of the exhaust sounds and stuff?