So I got my Fusion about 4 years ago and for about 2 and a half to 3 years, I've been having an issue where it will idle pretty roughly at stop lights and such. However, it RARELY does it at the first stop I hit, I typically have to drive it for a solid 15-20 minutes before noticing anything, and sometimes it never even happens. But once it happens once, it typically just continues to get worse from there. Some extra info, when it does occur, the car bounces pretty violently forward and back and the RPMs fluctuate about 300-400 RPMs.
The check engine light has been on ever since the issue started occurring, and this started less than a week after returning from a trip to Nashville, which I lived in central Missouri at the time, so a decent drive on the car there and back, and I noticed it as soon as it stopped pouring on my car one night. The code thrown was for an EGR Valve, which I've had a personal mechanic replace on his own time once, and then had a Ford Certified shop replace it again. Smoke test has been done with no issues and all the vaccum lines have been tested with no problems. Does anybody have any possible ideas of what it may be?