So I've been having issues with sluggishness while accelerating and poor fuel economy for awhile. Scan data from my elm27 iPhone app showed very high long term fuel trims, enough that it would set lean codes p0171 and occasionally p0174 (but not as often).



Checked the maf with my dmm and everything reports normal, so I was thrown off of it being the culprit for a few days.
Read somewhere about pre 2002 fords using the barometric pressure reading as a truth test for what the maf reported so I loaded that PID.
What do you know? It was reporting 1.74 psi, which is roughly equal to being 50,000 feet above sea level. I guess it thought it was in a Boeing 747.



The back wire in the original looked rusted up.





So, I changed the MAF. Got a junk yard unit for 50 bucks.
My fuel trims are now back in the normal range and no more bogging or slugging while accelerating. It's still too soon to judge fuel economy, but I bet it improves quite a bit too.

 

If you are using an oiled air filter such as a K&N, you are going to crap up the new MAF too.

 

Nope. Never used a K&N. That seems like the general assumption around these parts, but I am beginning to believe this truck had the front end buried up in mud at some point and got mud into the intake.

I should also point out another symptom I was having was erratic shift points. This has resolved, too.