The switch your looking at is the neutral start switch.
There is no other switch on the transmission. The throttle body controls the shift and its inside the transmission.
The lower cable on the ejection sustem is the cable thats controls shifting.
I suggest this.
Make sure you transmission fluid is clean and full. If not change it and the filter.
Make sure the throttle cable is hooked up and adjusted correctly. I doubt it could get much out of adjustment if everything is hooked up right.
What RPM does your car shift into high gear under light acceleration or do you have to let up on thr gas for it to shift.
The library has manuals. I bought a Chilton and that was not a good move. I have since bought a Haynes and its a lot better. ISBN 1 56392 311 4