i have a 2000 f-150 4.2l the check engine light came on the other day so i took it to a ford dealer to find out the problem they told me it was the MAF(Mass Air Flow sensor) i changed it out check enigne light went off but now im lacking on bottom end power and top end i replaced the stock MAF with an after market one can this be the problem or what??

 

I would try unhooking the neg battery cable for a few minutes to reset the computer. Then take it for a drive and see if reseting the computer helps it.

 

i did that and still the same thing does anyone have anymore ideas

 

It's possible that a new part is actually no good. I'd drive it for a couple of days, and let the computer relearn the data. Sometimes it can take a few driving cycles to smooth out after repairs/tuneups.

Dave