There was a recall on MANUAL TRANSMISSION Nitros due to issues such as yours. Many others have had issues on all other Nitros too due to a poor design. Some say that that the emergency brake is self adjusting but when it doesn't many times parts need to be replaced. Sorry not to be of more help. You might stop by a Dealership for advice since they must have dealt with this issue in the past.
NHTSA Campaign Number: 08V525000
Vehicle/Equipment Make: DODGE
Vehicle/Eqipment Model: NITRO
Model Year: 2008
Mfg Campaign Number: H28
Mfg Component Desc: PARKING BRAKE
Mfg Involved in Recall: CHRYSLER LLC
Manufacture Dates: 05-30-08 through 02-15-08
Type of Report: (V) Vehicle
Potential # of Units Affected: 3,663
Date Owner Notified by Mfg: 10-27-08
Recall Initiated By: MFR
Mfg Responsible for Recall: CHRYSLER GROUP LLC
Report Recieved Date: 10-08-08
Record Creation Date: 10-08-08
Regulation Part Number:
Defect Summary: CHRYSLER IS RECALLING 3,663 MY 2007-2008 DODGE NITRO AND MY 2008 JEEP LIBERTY VEHICLES EQUIPPED WITH MANUAL TRANSMISSIONS. THE PARK BRAKE LEVER CLUTCH DRUM MAY DISTORT AND REDUCE THE EFFECTIVENESS OF THE PARK BRAKE SYSTEM.
Consequence Summary: THIS COULD ALLOW THE VEHICLE TO MOVE INADVERTENTLY AND CAUSE A CRASH WITHOUT WARNING.
Corrective Summary: DEALERS WILL REPLACE THE PARK BRAKE LEVER ASSEMBLY FREE OF CHARGE. THE RECALL BEGAN ON OCTOBER 27, 2008. OWNERS MAY CONTACT CHRYSLER AT 1-800-853-1403.
Notes: CHRYSLER RECALL NO. H28.CUSTOMERS MAY ALSO CONTACT THE NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION'S VEHICLE SAFETY HOTLINE AT 1-888-327-4236 (TTY 1-800-424-9153), OR GO TO HTTP://WWW.SAFERCAR.GOV