On some ZJ Built between 2/6/94 and 1/8/95,Equipped with 4.0L & 5.2L may experience a slight sag or hesitation(bucking) on tip in acceleration. This may be more noticeable in high ambient temperatures.. To test and verify if this applies to your Jeep, you will need a fuel pressure test gauge to test the port on the fuel rail. Install the test gauge and be carefull of the pressurized fuel that will spray out of the rail. place a rag over it to keep the spray from getting to your face. after installing the gauge, start the engine and take note of the pressure @ idle. IF the pressure is above 47psi,. Replace the fuel pump module with part # 52018796..