2002 Ford F-150

Engine Performance problem
2002 Ford F150 6 cyl Two Wheel Drive Manual 135000 miles

My check engine light is on and I have had a local parts store pull the code and it says the MAF is bad. I replaced the MAF with a new one and pulled the battery to reset the computer. It drove fine for about 150 miles and the light came on again and when it was checked it said the same thing. So I returned the MAF I just bought and replaced it and did the same thing, 150 miles later it the light came back on again. I have looked at the schematics and cannot find what I should check next. What is the next step or possible culprit?
July 20, 2010.

Since it did the same thing with two different maf sensors, I would start checking the wiring to it for continunity. Chances are there is a break in one of them that is not making connection all the time.

Try that and let me know what you find.