vss viechle speed sensor wire location

i finally finished my motor rebuild/ tranny swap. everything runs and drives fine except the speedometer. i kept my auto harness and now i cant find where the plug in is for the vss. i don't know where to put the three wires coming from the sensor. any body know what wires it is on the computer or is it part of the auto trans plug that i need to tap into?

What motor?

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420a motor, i have the sensor plug with the three wires coming out of it,(yellow, yellow-white, green black) i just dont know where to put them. and now when i start it it starts, then in order to keep it running i have to pump the gas really fast back and forth untill it finnaly idles good. any ideas?