98 Windstar strats okay - rough idle after warm start on Humid day

Friends,
I am having a weird problem on my 98 Windstar 3.8 liter.
The van starts good in the morning (when cold) and runs fine.

After the engine heats up to normal and the van sits for 15 minutes, now if started the engine idles very rough for 2 minutes.

This happens mostly on a humid day only (not when rains or snows).

I have changed Cam position sensor, Spark plugs, PCV valve, DPFE, EGR valve and ignition coil.

The problem is still there.

Please help.
Thanks.

Hi there,

Have you checked for cracks on the vacuum lines? that would be a good place to start.

Best regards,

Oscar.

Hi there,

Have you checked for cracks on the vacuum lines? that would be a good place to start.

Best regards,

Oscar.
Yes , Wiswind had asked me to do that for some other reason and I have checked for all the vaccum lines and they all are intact.

Sorry I don't have any more ideas, it sound like a strange problem. Just to make sure whenever you notice the engine is running rough unplug the MAF harness, it might stall but turn it on again and see if this conditions goes away.

Best regards,

Oscar.

possible a fuel pump. check fuel pressure while its running bad. assuming there are no warning lights lit up on the dash