My truck runs too rich?

Dealing with a rich-running condition can be frustrating, especially when you've already replaced several components. Here are some steps you can take to further diagnose and address the issue with your 1999 Dodge Ram:

Check for Vacuum Leaks: Vacuum leaks can cause a rich-running condition and affect engine performance. Inspect all vacuum hoses and connections for cracks, leaks, or disconnections.

Fuel Pressure Check: Ensure that the fuel pressure is within the manufacturer's specifications. High fuel pressure could lead to excessive fuel delivery and a rich mixture.

Examine Fuel Injectors: While you mentioned replacing the O-rings on the fuel injectors, it's worth ensuring that the injectors themselves are clean and functioning properly. A clogged or leaking injector can cause a rich condition.

Exhaust System Inspection: Check for exhaust leaks, as they can introduce excess air into the exhaust stream, affecting the oxygen sensor readings and potentially causing a rich mixture.

Check Coolant Temperature Sensor: A faulty coolant temperature sensor could lead to incorrect fuel delivery. If the sensor is reading incorrectly, it might cause the engine to run rich.

Check for Faulty EGR System: A malfunctioning Exhaust Gas Recirculation (EGR) system can cause a rich condition. Inspect the EGR valve, passages, and related components.

Scan for Trouble Codes: Even if the Check Engine Light isn't illuminated, there might be stored trouble codes that can provide clues about the issue. Use an OBD-II scanner to check for any codes.

A faulty MAP sensor can lead to incorrect air measurements and affect fuel delivery. Try cleaning or testing the MAP sensor if you haven't already.

Examine the Catalytic Converter: A partially blocked catalytic converter can restrict exhaust flow and lead to a rich condition. Perform a back pressure test to check its condition.

Professional Diagnostics: Given that you've replaced many components and the issue persists, it might be time to seek the help of a professional mechanic or a dealership. They have access to specialized diagnostic equipment that can pinpoint issues more accurately.

Data Logging: If possible, use an advanced scanner to log live data while the engine is running. This data can provide insights into sensor readings, fuel trims, and other parameters that could be contributing to the rich condition.

Please check over this guide:

https://www.2carpros.com/articles/comprehensive-guide-to-diagnosing-and-resolving-rich-running-issues-in-your-automobile

Here is the location for the MAP sensor in case you want to swap it out. Check out the images (Below). Please let us know what happens.

Hmm, that's not good! I would check the o2 sensors make sure they are working properly, also clean the MAP sensor. See if that helps.