Some Jeep Grand Cherokee owners report experiencing a loss of power that prevents them from driving over 40 miles per hour, which can be attributed to several potential causes. These include issues with a dirty or clogged fuel filter that can lead to poor engine performance, as well as problems with fuel pressure or a failing fuel pump that limit speed and acceleration. Additionally, some owners notice that if the RPMs increase without corresponding acceleration, it may indicate transmission-related troubles. Regular maintenance, such as changing the engine air filter and using fuel injector cleaner, is recommended to prevent performance issues. Furthermore, a failing catalytic converter can restrict exhaust flow, impacting vehicle performance, and owners may find it helpful to remove the catalytic converter bolts for diagnostic testing. Other factors, such as bad actuators or spark plugs, may also contribute to inadequate power and loss of acceleration. Addressing these potential causes through maintenance and diagnostics is crucial for restoring optimal performance.