Sons 300m and I need help please!

I had a 99 Durango 5.9L. The way the systems were wired in that, the front O2 sensor heating circuit could fail and cause some weird issues. I don't remember for sure but it tied into TPS and crank sensor if I remember correctly. It would NOT cause the Check engine light to come on and wouldn't store a code. Also the statement above about the system being sensitive to after market sensors was true on it also. May try disconnecting the front O2 and seeing if it runs better, it will cause a check engine light and throw a code but should throw it into the redundant settings, basically open loop operation. Not sure on your 2001 300, but on the Durango you could display "discreet" codes on odometer by holding the odometer reset and turning on the key.