Do you happen to have the Check Engine Light on? Might be a good time to check. Cheap and simple to perform and even if you don't, great investment for the future to purchase a Scan Tool. Good Luck!
Dodge Nitro: Engine Problems / Code Errors
Check Engine Code Scanner | Advance Auto Parts
Nitro Year: 2007 (1 of 91,815 sold in 07)
Nitro Model: R/T 4X4 Stone White
CAT-BACK Exhaust, CAI, Projector Head Lamps
Fully-Equipped w/all factory options