On top of what's been said keeping the intake clean keeps codes away. The metal tube for the PCV and clog and throw codes and well as the area around where the TB connects. Those passages are essential to a clean running code free engine. Replacing the UIM/LIM gaskets is also good at least every 80k. They can become brittle and crack over time causing vac. leaks.

-'96 SE MTX 3L -'98 SVT 1,173 of 6,535 -'05 Mazda 6s, loaded, g/f's ride -Need a 96-00 manual on CD? PM or email me