97 dodge neon runs fine but smells like it is running rich and the smell is getting into the drivers compartment what would cause it to run rich?

A rich-running engine in a 1997 Dodge Neon can be caused by several factors, including a malfunctioning fuel injector, a faulty mass airflow sensor, or a defective oxygen sensor. Additionally, issues with the engine's air intake system, such as a clogged air filter, can contribute to an improper air-fuel mixture. The smell entering the driver's compartment may also indicate a possible exhaust leak, which should be addressed to ensure safety and proper vehicle operation.