99 silhouette Engine code PO101

Does anybody know really what this code is for. I have the manufacturer's service manual but it is very vague. I know it has to deal with the mass air flow or throttle positon assem. Van drives great but when on the highway you feel like it just had a hicup and then the engine light came on and when I scanned it the code was po101 any info would be great It has 167000 km on it.