EGR valve problem? 1993 Ford Mustang

1993 Ford Mustang 125000 miles. Recently, my car has had problems running. It runs roughly, and the RPMs keep dropping down and then jerking back up, with jerks in speed when this happens. In the mornings, especially when it is cold, it starts easily, but idles roughly, and dies often. After it dies it is often difficult to restart, and the car smells of fuel. When driving in the cold, the RPMs drop, the check engine light comes on, and the car stops accelerating, coasts to a stop, and dies. After it warms up, or the temperature outside is warm, it performs normally, for the most part. I have had 3 diagnostics run on it, but they tell me nothing is wrong. They suggested a problem with the ignition module, and I had that replaced, but the problem persists, and is growing worse. I have had a couple of friends tell me it is a problem with the EGR valve.
Does this sound like the correct diagnosis? Any help would be appreciated.