My truck is an 06 with the 3.0 and it has no EGR system. What would make it run bad after reaching operating temperature?

 

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See if there are any Codes in computer memory

Sensors used when cold are TPS, ECT, IAT and MAF
When warm, 3 O2 sensors are added, but having 3 O2 sensors fail at the same time would be impossible

Dirty MAF or failing ECT sensor would be likely suspects