something causing it to shake. at idle in park through highway driving, it never stops

My first guess would be a cylinder misfire -- and there are plenty of things to cause that, bad spark plug, ignition related or possibly valves or fuel injectors. One thing to look at is your motor mounts, if they are shot you ll get a vibration you dont like as well

I've replaced plugs,plug wires, and checked EGR. It seems like something out of balance.

possible broken engine mount

The Windstar Intake Manifold Runner Control (IMRC) is a common source of this symptom. Your engine has a set of flaps in your intake manifold that open and close to regulate the flow of fuel and air to the combution chamber. At the end of these flaps are tiny plastic bushing that often rot away and fall out allowing them to change the flow of air and fuel causing the engine to miss or shake. Once they are bad enough the mechanical linkage that attaches them to the electric motor that controls them may fall out. It sounds complicated but it is an easy and cheap fix. part #F5RZ-9F955-AB from the ford dealer they cost about $5 a piece when I bought my last set. Google the repair to find the pecise location with pictures as it is a little hard to explain the location. Hope this helps.

I have a 1999 ford windstar and what I want to no if them pieces fall of will it cause my van to vibrate real bad because I replaced at new motor mounts on it and but new pluges and wire and also replaced the coil pack to and it stell vibrants bad if any one knows if that would fix it are if anyone know what can fix it please email me I don't want my wife and kid to brake down my email is davids302011@yahoo.com thank you

I have a 2002 ford windstar and it shake real bad! When put it in drive so I'm scared to drive it. Feel like the engine. Want to jump out of the hood. I took a chance to drive it! And it drive real good! But when your stop in drive it shakes again!. But it never shakes in park. Can someone please help me? I would like to take my son to family house for Thanksgiving! Thank you!.

Check out this video by Scotty Kilmer! It talks about what could be the source of your problem and how to fix. Google this: Fixing a car that shakes when accelerating. (Link) https://youtu.be/EMVj5xl1Mzo

My 2001 ford winstar runs fine. But once im at a stop light. Major vibration coming from somewheres. Once I start driving it goes away. I have sat there while its vibrating and pressed on the gas. It's not coming from the engine.