I changed my spark plugs and cleaned my mass airflow sensor with maf cleaner. The truck didn't want to start but it finally did. When if did it had a sulfur smell but went away. The truck wouldn't idle on its own. I took it for a drive and it ran fine but at stop signs it would die. I started it today and it was normal until I drove approx 6 blocks then it would die when I rolled up to a stop sign. Could it be my AIT Valve? MAF sensor? PCV valve not on correct? We did unplug the computer to get to the back spark plugs. 2004 F150 5.4 4WD

carefully remove it from the air tube and use a spray cleaner especially designed to clean the sensor any automotive store sarries it
How To Clean Mass Air Flow Sensor MAF How To Clean Mass Airflow Sensor In depth detailed version How to Clean Your MAF Sensor

http://www.autozone.com/miscellaneous-cleaners-and-degreasers/electrical-parts-cleaner/crc-mass-air-flow-sensor-cleaner/36011_0_0/

Have to remove the PCM to to that spark plug
You most likely have a couple bad COP Ignition
Coils
The front O2 Sensor get replaced at 100,000
miles
I don't understand the question,run low
Now you cleaned the MAF Clean the Throttle
Body with CRC Throttle Body Cleaner

No, no specific problem-well, maybe a bad MAF. Buy a can of MAF sensor cleaner from Walmart or parts stores, or any sensor-safe cleaner, and try cleaning it. If that doesn't help, try a sensor form a salvage yard.

It could be a dirty (MAF) Mass Airflow Sensor or a dirty Throttle Body, Get some MAF cleaner at your local auto parts store and take apart the plastic ducting that attaches to the Throttle Body and use the cleaner on the inside of the Throttle Body and MAF sensor. Cleaning this takes off the carbon build-up and dirt which affects throttle response.

Rough Idle covers several symptoms. Do you mean Idle (RPM) goes up and down or do you mean it is too low and car tries to stall? Idle is dependent on fuel delivery and spark Depending on your mileage and driving style it is more likely an Idle Air Control valve, Mass Airflow Sensor or Throttle body. I would purchase CRC MAF Cleaner and CRC Throttle Body cleaner. you will need to disconnect the induction hose from the air filter and throttle body. On the Taurus/Sable the air filter is loated on driver side under hood. Trace back from it and mid way youwill find a plastic cylinder that is wired in with a plug. Unplug the MAF. Make sure and notate which side is facing the engine as the air flow has to be the right way. I put a dot on the side that should face inward to remember the flow direction. Find a ventilated area and take the CRC MAF cleaner and spray the inside of the Mass airflow from about an inch away. Be careful there are very fine wires inside that can be broken by the nozzle by touching or being too close when spraying. Spray liberally and then set aside to dry. Continuing up the intake you will find the throttle body whihc is a cirucular intake that is metalic It has a butterfly valve inside. Use the same CRC brand but this time us CRC Throttle body cleaner. DONT USE CARB CLEANER OR OTHER BRAND. Ford coats their Throttle bodies with teflon and any other brand can eat this lining away. Clean in short bursts. You can gently take a clean shop rag to wipe inside with your finger as sprayed to dislodge some of the dirt, but be gentle. Dont use stiff brushes.. A qtip, a soft bristle tooth brush with very light pressure. as well. Clean it very well. Place rag underneath to catch any run off. After its cleaned and teh MAF is cleaned, replace the air filter and reassemble the unit. The car will be hard to start at first. Turn it over a few times and it will start. It will sputter a bit and then should run better. Start with MAF and Throttle body first. then move to plugs..Finally, the MAF and Throttle body should be cleaned every other oil change.

Rough Idle covers several symptoms. Do you mean Idle (RPM) goes up and down or do you mean it is too low and car tries to stall? Idle is dependent on fuel delivery and spark Depending on your mileage and driving style it is more likely an Idle Air Control valve, Mass Airflow Sensor or Throttle body. I would purchase CRC MAF Cleaner and CRC Throttle Body cleaner. you will need to disconnect the induction hose from the air filter and throttle body. On the Taurus/Sable the air filter is loated on driver side under hood. Trace back from it and mid way youwill find a plastic cylinder that is wired in with a plug. Unplug the MAF. Make sure and notate which side is facing the engine as the air flow has to be the right way. I put a dot on the side that should face inward to remember the flow direction. Find a ventilated area and take the CRC MAF cleaner and spray the inside of the Mass airflow from about an inch away. Be careful there are very fine wires inside that can be broken by the nozzle by touching or being too close when spraying. Spray liberally and then set aside to dry. Continuing up the intake you will find the throttle body whihc is a cirucular intake that is metalic It has a butterfly valve inside. Use the same CRC brand but this time us CRC Throttle body cleaner. DONT USE CARB CLEANER OR OTHER BRAND. Ford coats their Throttle bodies with teflon and any other brand can eat this lining away. Clean in short bursts. You can gently take a clean shop rag to wipe inside with your finger as sprayed to dislodge some of the dirt, but be gentle. Dont use stiff brushes.. A qtip, a soft bristle tooth brush with very light pressure. as well. Clean it very well. Place rag underneath to catch any run off. After its cleaned and teh MAF is cleaned, replace the air filter and reassemble the unit. The car will be hard to start at first. Turn it over a few times and it will start. It will sputter a bit and then should run better. Start with MAF and Throttle body first. then move to plugs..Finally, the MAF and Throttle body should be cleaned every other oil change.

Probably not. Depending on your mileage and driving style it is more likely an Idle Air Control valve, Mass Airflow Sensor or Throttle body. I would purchase CRC MAF Cleaner and CRC Throttle Body cleaner. you will need to disconnect the induction hose from the air filter and throttle body. On the Taurus the air filter is loated on driver side under hood. Trace back from it and mid way youwill find a plastic cylinder that is wired in with a plug. Unplug the MAF. Make sure and notate which side is facing the engine as the air flow has to be the right way. I put a dot on the side that should face inward to remember the flow direction. Find a ventilated area and take the CRC MAF cleaner and spray the inside of the Mass airflow from about an inch away. Be careful there are very fine wires inside that can be broken by the nozzle by touching or being too close when spraying. Spray liberally and then set aside to dry. Continuing up the intake you will find the throttle body whihc is a cirucular intake that is metalic It has a butterfly valve inside. Use the same CRC brand but this time us CRC Throttle body cleaner. DONT USE CARB CLEANER OR OTHER BRAND. Ford coats their Throttle bodies with teflon and any other brand can eat this lining away. Clean in short bursts. You can gently take a clean shop rag to wipe inside with your finger as sprayed to dislodge some of the dirt, but be gentle. Dont use stiff brushes.. A qtip, a soft bristle tooth brush with very light pressure. as well. Clean it very well. Place rag underneath to catch any run off. After its cleaned and teh MAF is cleaned, replace the air filter and reassemble the unit. The car will be hard to start at first. Turn it over a few times and it will start. It will sputter a bit and then should run better. The plugs on modern vehicles are set to run 100K miles or more before changing and unless you are burning oil and fouling them out they should be fine. Start with MAF and Throttle body first. then move to plugs..Finally, the MAF and Throttle body should be cleaned every other oil change.

The mass airflow sensor could be fouled out. If you have a K&N or other oilable filter, it can let oil get on the sensor and foul it out. Buy and use a dedicated MAF cleaner. Don't use anything but a dedicated MAF cleaner. If cleaning it doesn't work, then you should replace the sensor. Expect to pay over $200 for a new sensor.

MAF stands for mass air flow sensor, this is used to tell the computer how much air is entering the engine, check the air filter,and clean the sensor with CRC mass air flow cleaner, with engine off. hope this helps,let me know Ray