Hi my name is XXXXX XXXXX Your complete satisfaction is my goal. Please provide as much information about your concern as you can.
Are there any trouble codes setting? 14, 15, 33, 34,45? Have you checked the EGR valve for being stuck open slightly?
I would inspect the EGR valve, and also relocate the MAP sensor hose from the rear of the throttle body to another manifold vacuum source.
Next I would inspect the coolant temp sensor circuit for the ECM. if it is open or has high resistance, it will read , like the engine is cold, and the ECM will deliver fuel, like it is a cold start, and this will be too much when the engine is warm.
Try disconnecting the o2 sensor. if it runs better, then you may have an o2 sensor that is reading lean all the time. also inspect the o2 sensor wire to make sure it is not shorted to ground. this also will tell the computer to give the engine more fuel.
If you need more information, let me know.