While solving the low boost problem I had we didn't disconnect the positive from the ecu (only the negitave) we eventually worked out we needed to reset the ecu. And remove the positive and replace it. However when the ecu was not reset (not working) my van idle was perfect. This lead me to rule out a mechanical fault for the rough idle. Surely the ecu or sensor or something controlled by the ecu is causing the rough idle. Any suggestions?