2K Pro 1.8L P0171 DTC

Has anyone had the annoying P0171 trouble code (lean condition) on their 1.8L Protege? My wife's 2000 Protege has around 50k miles and this code keeps coming back. Before changing the plugs, cleaning the MAF, checking for intake leaks and replacing the PCV valve, it would come on instantly after erasing it. Now it comes on every so often. Any thoughts? It's driving me crazy. I would hate to start replacing more expensive components without a full understanding of the problem.

Had the same code on my daughter's 99ES 1.8L. A piece of the intake manifold gasket went AWOL (pretty big one too!). Try spraying carb cleaner along the joint between the manifold and head while the car's running - if you get a stumble, you found the problem. Don't know about the 2000, but pretty common on the 99 (Mazda has a TSB out on it).

sound like you have a bad mass air flow meter.