I had a 2000 4.4i for which the SEL was illuminated but the vehicle drove without any obvious symptoms. While investigating the problem I became 95% sure the MAF was to blame. However given the high price of an OEM MAF I was hesitant to buy one on the chance it might not be the problem. So I picked up a low cost (think it was $110 or so) aftermarket MAF. After installing the SEL cleared and I was happy. Until the vehicle began to experience unexplained hesitation and stumbling on occasion. I took the vehicle to a mechanic a friend referred me to and he installed an OEM MAF in order to diagnose the problem. After driving the vehicle for a couple of weeks with no problems I called him up and paid the $350 for the MAF. In the end the aftermarket part ended up costing me more money than just buying the OEM part. If you know it's the MAF my experience leads me to the conclusion to go with the OEM part.