What exactly is your problem? You are asking about missing sensors, could you specify which ones? As far as splicing goes, you will have to if you do not have the turbo body harness. Is this what you mean when you say that you have the harness? THere is an engine and a body harness to deal with.
Do you know the year of the engine? I might be able to find my old pin breakdown of the kickpanel if you have a 93jdm turb and a 91 N/A, not sure if it helps for 91,92.
Ok i have a 1991 mr2 NA and I got a motor and tranny from a 91 92 3SGTE but when i got the 3sgte motor it came with a cut harness and then i got a wiring harness but i only have the map sensor, igniter, and the throttle sensor and i think thats it. and so im was wondering if there is a way to wiring the wiring harness on to the motor without the other sensors??