I've had this problem since I bought my truck, it revs up pretty nicely but it doesn't seem to come back down that quick. From like 4k down it takes it about 7-10 seconds to return to idle. Is this normal or no? BTW, it's a 2k 4.8 auto.

 

Depending on where you are in the Airflow Decay tables of the pcm, it can take a while to fall back down in rpms in park/neutral. 7-10 seconds seems long though. I would guess I take 3 seconds-ish.