I have a 2001 jeep liberty sport and recently it has been having some problems. I've noticed that after driving for long distances the engine runs much rougher, especially when idling. Also there has been a faint smell of something burning (rubber) for the past couple of days and just today it began to smoke and overheat, although the temperature gauge reads normal. The trouble comes and goes, sometimes the car runs smooth and quiet other times it feels like it's trying to die at stop lights. I cannot see a leak nor do any of the hoses appear damaged. The fluid levels were all normal except for the coolant which was low, but not low enough to warrant the overheating. Any advice that could help point me in the right direction toward solving the problem would be greatly appreciated.