#1 misfire ONLY when it rains
 

2004 MPV

Every time it rains I get a check engine light and it is at least #1 cylinder misfire. Changed rear bank coil and plugs and the #1 again 5,000 miles ago.
Just rained and back again.

Any idea what cover is missing or real fix?

Still a P0301? I know it's a little bit of work but, move your rear bank coils to the front and put the fronts to the rear. Don't clear the codes or you'll have to wait for the PCM to relearn cyl position. Put a small amount of dish soap into a hand held spray bottle and fill the rest with water. Simulate a rainy day by misting the solution around the coils for a minute or two or until the misfire returns under engine load. Check your codes and see if it moved to the front bank. i.e. P0304 05 or 06. This will confirm a bad coil. if it stays a 301, check your connection at the coil and at the harness.