You should fix the codes, first check vacuum lines and then your intake manifold the intake manifolds are notorious for warping. I used to own a ‘99 with a 4.0L and that’s what it was on mine, as for the mass airflow sensor it will only be dirty if you are using an oil performance filter like K&N or Green


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2011 Ranger XLT 4x4 3.73 8.8" Trac-lok #1 T-bars, K -springs, LineX bedliner, General Grabber AT2's, Tonnopro tri-fold, CoverKing Realtree AP seat covers, OEM pre-keys, axle spacers, Bilstein 4600's, Hellwig AAL. Ziebart Undercoat
'98 Ranger XLT 2WD (sold)