Look coming out of the square block on the firewall where the main wiring block plugs into.
There will be a yellow and an orange wire that lead to a small double plug (actually 2 singles hooked together) about 8" away from the main wiring block.
The Yellow leads down to your kickdown on the driver's side of the transmission. It is a direct wire from the plug to the transmission. Basically a direct line from power, to the kickdown switch, to the transmission.
The orange leads down to the transfer case. It will plug in on the passenger's side of the case(beside the speedometer cable), and just lights up the light on the speedometer when it's in "emergency drive". Basically a direct wire from the switch in the transfer case, to the light bulb in the speedometer.
At the gas pedal, check for power coming into the the switch, it should have power. Trip the switch with your finger, you should then have power coming out of it. Check for power at the transmission plug. My wire was melted in half by the exhaust. The coating looked fine though.
The early shifting is probably a problem with your vacuum actuator. We can cover that after you get the kickdown switch taken care of.
I've been through the same thing with mine. Got it shifting like a champ now.