A clogged transmission filter can produce transmission slippage, engagement problems and hesitation. Experts recommend this filter be changed every 12,000-15,000 miles to extend the life of your automatic transmission. Other Maintenance Parts Many maintenance parts are mistakenly seen as non-critical. Plus, as emission laws have gotten more stringent, these parts have become essential - if you want your car to pass emissions the first time around. A worn oxygen sensor drastically changes engine settings.
Many major systems depend on manifold vacuum for signals and function.
All vacuum hoses should be checked and replaced as needed. Temperature sensors for various engine functions can also be a good weekend project. These sensors control the fuel injection system, cooling system and even the exhaust system. And they can definitely be a cause of poor performance problems. A clean engine runs cooler and is much less likely to cause premature failure of other parts.