Have you considered this hurricane maybe a blessing in disguise? If you have comprehensive insurance coverage, inocently park it in a flood zone and cut your losses! Then you can start with a fresh new van with its own set of problems!?! You may be better off!!!
Ok, ok. On many of the things you mentioned on this fan stumble business and bad mpg, I just don't know how to procede. If you have all new plugs, wires, whatever and no codes, I'd wait on the coil. I don't know 100% if it has an icm or if that is part of the pcm, but it makes you wonder about the two. If it does, I thought that it could cause mpg problems. At a parked idle, does it ever have sooty exhaust?
On the electrical issue, I'd make sure the battery and alt are strong, which I think you've done. Does the alt light ever flicker? So my next suggestion would be to be sure you have clean and tight grounds for the fans, the body, block, ignition. A bad ground to the fans will cause a voltage drop and spike and a current surge to the fans. I wonder if the shielding for interference for the ignition isn't right, though that might code too.
I doubt changing the ect would help the electrical issue, but if it's values are off it could affect mpg. It's cheap and easy to replace. Be sure to buy a brass and not a plastic one, but if you are confident in what you measured to be ok, then don't bother. A trick or test of a sort to see if the ect has any influence on your fan maybe, is to with a warm engine, pull the connector to the ect causing the fans to come on and then reattach it causing the fans to go off, as long as the engine isn't too hot to need the fans on at that moment. If the problem still exits, I'd think that would rule out the ect, which I doubt anyway would be the culprit, as it only sends a signal to the pcm and the pcm sends a message to the ccrm to turn on the fans.
On the same line of thinking, the iat may be worth testing, as it too affects fuel, egr, etc.
You may be able to measure current with your meter, but usually very little fused. Often in a different jack you can measure more, but unfused.
I'd think if you have a problem with the FPR, you would more than once be able to smell gas. I assume you are smelling the vac line to it, which if there is a leak, would suck it up, so that you could smell it and if enough, cause some surging or emission code, which you aren't.
I can't offer anything on your list of parts going bad as none have. Have you searched for bad mpg and fuel? I've had fp issues, but none that cause mpg problems.
I have the same problem getting the ww fluid to come on too. Sounds like the new window switch is backwards. Any chance the wires were swapped putting the connector on? You may be able to release the two wire pins inside the connector and swap them. The switch simply alternates polarity to the window motor, but the input or output is reversed.
I still think you should consider the flood and insurance angle.
Good luck man. You and the rest of you down there will need it!