- remove the MAF from the car
- spray some electrical contact cleaner or non-chlorinated brake cleaner (something that leaves NO residue) through the sampling tube over the wires.
The MAF should be clean inside. If not, you have a leak that is letting air in that isn't being filtered. The wires may or may not look slightly off color. They can become oxidized over time, which can affect readings. Excess oil from a K&N or other open element filter that has been over-oiled can foul the wires, as well.
- reinstall MAF