My jeep had the check engine light on and the p0406 code. I replaced the EGR along with all plugs and new wires. The initial issues were very rough acceleration and shifting and no power and obviously terrible gas mileage. My idle is not bad though which confuses me. Its mostly when accelerating that is rough. After replacing the egr, it ran great driving for the first day. Power was back and it was smooth. The next day got in fired it up and ran like complete garbage again. Running the same way before the new egr installation. I currently have no pending codes and check engine light has not came back on. But granted only put on about 60 miles since new egr. Anyone have ideas where to start? Throttle sensor? Bad egr? Thanks in advance

 

Bad EGR is possible but I'd check that all the bolts are tight first. A little air leak will make it run poorly.