I did a search but couldn't find anything that sounded like my truck issue. I have a 2002 f 150 4x4 5.4 v8 with around 125000 miles. The issue started sometime back when I was driving down the road. I had been driving for a while so truck was at normal operating temp and had been for a while. It started to act like it was going to die or like you took your foot off the throttle then it would run normal for anywhere from a second to several minutes. At an Idle it will run from around 800 rpms to 1200 but wont stay at a smooth Idle. I can mash the throttle down and it will smooth out until I let off and the it does it again. Gets worse when I ease off the throttle. It finally threw a code and a mechanic said it was the mass air flow sensor and he changed it. It ran fine for about a month then started again. I was told to clean the Mass air flow sensor and did and it would help for a while, maybe a day or maybe a month. I ask another mechanic and he said my K&N air filter could be the problem as Oil could be coming off and getting on MAF sensor and causing problem. I replaced it with a regular filter, cleaned sensor again and ran fine for a few days. now its back to the same thing. Last time I cleaned the MAF nothing changed. So do I need to replace the sensor and try it again or Is there something else I need to look at? Does it have a throttle position sensor or cam sensor problem? Idle control sensor? Thanks for the help.

 

Was the MAF a genuine OEM part or aftermarket? Sometimes it doesn't matter, sometimes it does, especially with electrical parts.

Welcome to FTE btw

 

what is the actual CODE you are getting ?

 

They were not OEM so I may have to try that
​​​​​​​It has only thrown one code in the several months I have fought this and I don't remember what it was.. It was reset when the mechanic put in the new sensor. I wish it would throw a code so I could check it.

 

No it was a part from local parts house. I think I may try a Ford sensor and see if that works. I cleaned it again last night and it ran fine today on the way to work and back, 30 miles one way.
Thanks for the response and welcome.

 

It only threw a code after the second or third time it acted up. The mechanic replaced the sensor and cleared the codes. I don't remember what they were. It has acted up around ten times since but has never thrown another code. I wish it would so I could take it to the dealer and have it checked. Thanks for the response.

 

In my experience cleaning the MAF is usually a temporary fix, they go bad again after a little bit. I would bring back to the parts store as there is probably at least a 1 yr warranty on it.

 

Have you ever cleaned the throttle body and idle air control valve? If not remove the air filter housing and tubing connection at the throttle body so you can see the throttle plate. Open the throttle by hand where the cable is attached. Check with a flashlight or run your finger under the backside of the throttle plate when open. If it's full of black sludge buildup remove the throttle body and IAC and clean with throttle body cleaner and a soft brush only.

 

I replaced the Maf sensor and it ran fine for a few days but now it started to do the same thing again. running down the road it will drop rpm's then recovers, it doesn't die and may go for miles just fine. At an idle it may run fine or may drop from 1000 rpms to 5-600 then back up to idle again. I haven't checked or cleaned the Throttle body but I will look at it. Could the idle sensor or throttle position sensor be the problem?

 

I'll echo the cleaning of the throttle body housing, remove it and then cleaning is much easier and more thorugh. The IAC will come with it and is much easier to cleaning it as well.

The only thing to add is to check those connections to the MAF sensor and make sure that they are making good contact. ALSO check the connection to the Crankshaft position sensor.

Have you checked for vacuum leaks? have you changed the fuel filter?

 

I will clean both as soon as I get a chance. I wondered about the cam sensor but hadn't thought about crank.
I have checked for vacuum leaks and found none. I don't think it is a fuel problem because of the way it acts. Its more electrical because of the suddenness of it. I have had fuel filters plug or partially plug but this doesn't act that way.

 

Its my understanding that the Crankshaft Position Sensor provides signal for the spark and fuel delivery