Q: I have a 1999 jeep Cherokee XJ that idles fine but when I accelerate it spits and shutters. Any ideas?

Check engine compression and intake vacuum to first rule out possible mechanical problems such as stuck or leaking valves. Among the causes of poor acceleration are clogged fuel injectors and/or inadequate fuel pressure/volume. When an injector is clogged it can degrade the performance of the vehicle and the car may accelerate slowly or feel that it does not have enough power. A defective fuel pump will not supply enough fuel to the injectors. This can cause the vehicle to accelerate slowly, or even sputter and stall, especially at high speeds. A clogged fuel filter can also restrict the amount of fuel that reaches the injectors. A dirty mass airflow sensor can cause the wrong data to be be sent to the computer. A slow accelerating car is the result of this incorrect data. It may also trigger the Check Engine Light. Other causes of poor acceleration are vacuum leaks, a defective throttle position sensor, a defective idle air control valve, and a plugged catalytic converter. To get the underlying cause of the problem pinpointed and resolved, you can request an engine diagnostic for slow acceleration and the responding certified mechanic will get this taken care of for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.