Where is the fuel relay for a 2006 Toyota Sienna van?

Under normal conditions, the camshaft sensor contributes to the efficient timing/firing of coil plugs and fuel injectors.

wrong connection of the fan wire you have to change the wire polarity

That's a possibility, but before you investigate that, as it's a smaller possibility, please check the following:
1) Spark plugs, leads and coil(s)2) Fuel filter and pump3) Air filter.
Those are the more probable issues which often cause faults such as this.

When you say FAN I presume you mean radiator fan. This will run if it thinks the engine is very hot. You may have noticed on a hot day the fan will carry on even when you take the keys out. In this case it could be the thermostat for the fan thinks it's too hot.

Check the fuse marked "power outlet" on the fuse panel inside lower left of the dash, there may be more than one marked like this.

Bank 2 is down on the exhaust past the catalytic converter

The arrow indicates which side of the van the fuel door is located on.

Exactly five quarts to do an oil change on this van assuming you are also replacing the oil filter.
How long between oil changes is typically recommended to be 5000 miles by Toyota. The van's service reminder light comes on at 5000 miles just for this purpose. To increase that interval is your choice.

Dealer Item ` $200
Junk Yard ~ $100
https://toyotapartscenter.net/toyotasiennaparts.html?gclid=CPX5u8HUlZ4CFSn6agod6Ae1oQ sells them for $167.17 + shipping and tax
PH; 800-516-1455
I recommend a pull, light tap and reconnect, recheck B4 buying. Also, shop manual has proper test procedure, Pages BE16-17