Engine Performance problem
2002 Ford F150 6 cyl Two Wheel Drive Automatic 160000 miles
/Truck sounds like it is " missing" while idiling. When it is running down the road, slight exceleration will cause the engine to run rough. The truck is also using way more gas then it should be. I have replaced the plugs and wires, and had the fuel system cleaned out. Oil changes have been on time. What needs to happen?