Had this happen on a diff vehicle

I just went thru the same madness on a 2005 Ford Focus. Not a soul believed me but it was my bfs money paying for the repairs so they just kept going... When every possible solution was exhausted....(except mine) they finally listened to the GIRL. It ended up being a problem with one of the EGR hoses behind the engine. The hose was $175 its self but it fixed it. Hopefully this helps someone to stumble upon this thread in the future.