low mileage and JDM dont belong in the same sentence unless the motor came in a front clip and odometer, but thats besides the point.
USDM Supras run EGR, JDM do not, hence JDM motors are not equipped with a EGR system.
You have two choices, you can put an EGR system on your JDM motor, or you can get a JDM ECU to go with it.
Doing neither is a bad idea, here is why:
The EGR system is designed to increase fuel economy and reduce emissions. It does this by reintroducing exhaust gas (inert) back into the combustion chainber at part throttle up to 4000rpm iirc. In this situation, 30% of the space in your combustion chainber is filled with inert exhaust. The other 70% is air from the intake. The ECU only injects 70% of the fuel needed otherwise. So if you dont have an EGR system, you get 100% air, but only 70% fuel aka lean aka bad.
The solution:
A equip the new motor with the EGR system off the old motor. This is a good idea, especially if you need to pass emissions.
or
B Find a JDM ecu. This would be programed for a no EGR set up also solving your problem.
My Reccomendation:
Swap your entire Intake Manifold and all electronics sensors exc. from the old motor to the new motor. with the intake manifold take the EGR valve and plumbing with it. You will also need to take the aforementioned EGR cooler with you. It is bolted onto the back of the head with 8 bolts 10mm iirc. The new motor will have block off plates over the EGR ports. Remove them and then install the EGR system along with everything else. This may seem like alot of work but will save you alot of headaches long run.
On that note I'm goin to bed. Feel free to PM me if you have any questions.