ecu

i did a 5sgte swap and im using the 5sfe wiring harness + ecu. surprisingly its still running decent but im barley putting any boost on it. also when i go fast or on the highway the engine sometimes goes lean. clearly i need to reflash the ecu amongst other things. does anyone no how to reflash the ecu (obd1)? or where to get it dont if its impossible to do it myself?