Greetings,

The check engine light came on my ‘94 4.0 and the code indicated a faulty EGR valve. The car ran well after the check engine light came on. The only indication something was wrong was the light.

My mechanic replaced the EGR valve and the check engine light never returned. But the car ran terrible. Very rough idle and just generally missing. I had another EGR valve put on. The car now idles great and seems to run well during normal driving. But when driving slowly, like 15 - 25 MPH, it’s missing. I can hear it missing through the exhaust. It also seems to be surging a little.

Does anyone have any thoughts on what this could be?

Thank you

 

IACV (Idle Air Control Valve) - your description fits the bill?

Does it happen when the engine is cold, or only once it's warmed up?

 

Thank you for the response! It happens all the time. Cold and warmed up.