I have a 2002 expedition 5.4. Initially my problem started with the typical coolant leak from my intake manifold. It never overheated and had water in the reservoir still. This is a joke to me really cause my dad was a mechanic and god forbid JB weld, but I'm on disability and once a month pay. In other words I'm broke for another week. So the JB weld fixed the leak. Now it is running rough. Somewhat the way it would act if I had a bad coil, except it is slightly surging. Runs fine at first start from cold. Then when you stop for a bit then go to start again that's when it runs rough. No engine light so I'm sure it isn't a coil. I'm pretty confident that I'm right on having to just replace the intake manifold. I just want some more opinions. I don't have my dad around anymore to help me figure it out.

 

While fixing the manifold you may have moved around some of the vacuum lines.
Check the PCV hose elbow and other vacuum lines for cracks or soft spots.

 

See if you have coolant in a spark plug well near the leak