How to tell if Parking break is hangingor sticking

Alright so i have noticed a diecrease in gas mpg about 2mp and nor sure if related to vent control valve sticking or I have heard about others parking break hanging/ sticking almost like going against the vehicle and not allowing to to fuly drive like being held back. Weird because when I am driving my wifes 07 qx and I let off the gas to cruise it sort of feels like i am being pulled back slightly in decleration not sure because mph still show consistent. But ither way how can we tell if the e break is still sort of engagued if no lights on and e break pedal is full up as if to say not engauged?

yeah just realized i spelled parking brake wrong cant edit to late :)