I have a 2000 F150, with 5.4, 125k. 3 Days ago, when I started it to leave school, it was running really rough. Idle wasn't really low, but it was shaking the truck like crazy. Drove on and it really didn't have much power at all until it hit 2200-2300 RPM. The rough/shaking idle has went away, but it is still running fairly poor until it hits 2300 RPM or so. There is no CEL, so all I can come up with is the MAF. Anybody have any ideas?

 

Have you tried cleaning the MAS with electronics spray cleaner? Have you been offroad or in water, or do you have a filter that uses oil, has it been re-oiled recently... Any of those can dirty up the sensor wires in the MAS. I'd probably start with that, clean it, then reset your computer by disconnecting the battery for bit. Then run it and see if it cures it. Let us know the outcome...

 

I actually cleaned the MAF with electric parts cleaner about a month ago. I do have a K&N, but I havn't re-oiled it since I cleaned the MAF.

 

If you got too much oil on the K&N it could have made its way to the maf.

 

I know, but the last time I reoiled the K&N was probally 6 months ago, so I would figure that It would have gunked the MAF up long ago. And I have cleaned the MAF betwee now and then.

 

Have you checked for any vacuum leaks? Listen for hissing sounds under the hood while engine is running and check all vacuum lines. Also, are you running a chip or tuner program?

P.S...

Have you reset your computer?

 

Checking for a vacuum leak is next on my list. I am not runnign a tuner or chip. There is a hissing/shuttering noise under acceleration, but I'm 90% sure its just an exhaust leak.

 

Original symptoms sound like a typical misfire. Just not severe (yet) enough to set the CEL.

If you can get your hands on a decent scan tool, go in and look at the MISFIRE PIDs and see which, if any, show elevated counts.

Steve