I have read for hours on hear trying to figure this out. I have used the search before some one ask.
I have a 2001 f150 with a 5.4. It has not been idleing when it gets cool out. It will serge read bad. after it would warm up real good it would do fine. Yesterday it did the same thing and was running good after it warmed up. Then it started to miss real bad while driving. Would idle fine while sitting at light. It would do a little better if I turned the overdrive off, With it on it would realy jump and buck.
I have a hypercherger programer an it gave the code PO 171. I got on line looking and found where to clean the MAF. I took it out and sprayed it down real good. Not it will not idle at all have to give it gas to keep it running. So I would think it is bad and is the problem? I was just wanting to ask before I went and bought a new one.

Thanks Tim

 

Did you use proper MAF cleaner or QD cleaner? Don't use anything that leaves a residue, like an oil/cleaner lubricant and make sure it's totally dry before reinstalling. Don't forget to reconnect the connector. If your running an oiled air filter, excess oil may have transferred to the MAF sensor.

 

Lime1Gt I used some connerctor cleaner I had in the garage. I think one of the problems was I sprayed it down an reistalled everything and started it. Probably didnt give it time to drive. I did go buy a new mass air flow and replaced the old one. Hope it fixes it.

Thanks again Lime1GT

 

From your discription, I am detecting 3 possible problems that may cause you confusion.
First, clean the IAC by removing it and spray cleaning it so the internal valve slides freely against it's spring.
This item directly controls idle. If it is gummed and sticks, all bets are off for a controlled idle.
Next, you may have one faulty coil causing the missfire and studdering in OD and light throttle. The joy of it is, it does not set a code to tell you what cylinder it is because it's not a 'hard' fault.
Next the 171 code could be an air leak from a faulty rubber part some place on the intake manifold.
Last, I cannot tell you, but the programmer may be causing some issue.
Look at all the above, then if you still have some issue back out of the modified program to see.
Good luck.

 

Ok I replaced the MAS and it fixed my miss I had. It still does not idle right. When you start it in the morning when it cold. It use to idle hight I guess like a choke so it would warm it up. Now when I start it. It only will idle at 500 rpm. I have also replace the IAC on iit tonight. Anyone have any ideas please let me know.

Thanks Tim

 

If there are no other issues, the computer has to relearn cold start and hot start conditions.
A way to get it to do that faster, is to reboot the computer by removing battery power for a couple minutes then start the motor from a cold start condition with some extra drain to load the motor more.
Let it fully heat, then drive about 5 miles and so several hot restarts.
If there are no other issues it should be perfect starting under all conditions.
Good luck.