96 windstar misfire no 5 cylinder

I am having a misfire problem. When I drive the van for about 30 minutes, shut it off for about 10 minutes and start it up the engine misfires and stalls or the check engine light comes on. Once I start down the road the problem goes away. It also has a rough idle. I had a full diagnostics done and the only thing it showed was a misfire in the no 5 cylinder.
Could somebody please help it is driving me nuts.

I've got one on cylinder 1. There is a Technical Service Bulletin (TSB) out on the problem. Likely the intake needs to be replaced, which I got a quote for $1,100. There are some other possibilities as well, like a bad spark plug, fuel injector, and a couple other things I don't remember.

Verify that all your routine maintenance items are done. Spark plugs, Air filter, fuel filter, PCV valve, MAF cleaned, Fuel system cleaner, etc.

If you still have the original battery....replace it. Sometimes....in many cars....funny things happen when the battery starts to get weak....as in a lower voltage...and greater load from excessive charging. It ....is a routine maintenance item at some point in 8 years......Verify that the battery connections are clean and tight.

For Spark plugs, make sure that DOUBLE platinum plugs are used.... Autozone stocked the plugs for the '96 3.8L under "stock code 686"....same ones I got at the dealer (Autozone was out). I would also stick with a Motorcraft PCV valve as a few people have posted that they had issues with some of the aftermarket brands (too much air let through).

The upper intake manifold for the '96 is pretty good. There are issues with the bolts / gaskets for the '99 and newer ones.