I have a 1998 Cherokee Sport, 4L 6 Cylinder engine. 146,000 miles.
For about a year and a half I have an issue with jerky acceleration at lower speeds. Around the same time I started experiencing some problems with a rough idle. When the engine is cold it idles very loudly and the RPMs oscillate in an inconsistent pattern. During this, the exhaust system is very loud and is shaking underneath the vehicle. On several rare occasions the engine has shut off because the RPMs have dropped so low.
I’m not sure if the two problems (idle and acceleration) are related. It feels like the same thing because my RPMs also fluctuate when driving at lower speeds. When this happens and the RPMs drop, it feels similar to running out of gas. Also when the jerky acceleration happens, I hear a clunk/click and I can feel that clunk/click in the gas pedal. Spark plugs were replaced just a few months before this all started.
This happens very inconsistently. I had a mechanic look at it, but it wouldn’t happen when he was in the car. Lately, it has become less inconsistent and happens almost every time I drive. Outside temperature seems to have no effect. It almost always stops after a few minutes and the engine is warm. But even this is inconsistent as sometimes I will drive for a long time, stop the car to gas up, and the problem is back even though the engine is plenty warm. The only consistency is that it’s always at the beginning of my drive. This never happens after accelerating away from a Red light for example.
Things I’ve tried:
- Tested fuel injectors (all fine)
- Manually cleaning fuel injectors
- Manually cleaning idle air control
- Using a fuel conditioner/additive somewhat regularly for the past 6 months.
- Tested Fuel Pressure (was fine the one time I checked it)
Any ideas? Thank you! First time poster, long time reader.