I don't know why people make this so complicated to explain. It just isn't.
Here is how to adjust. Put front of the car on jack stands or ramps so you can get under it. Block the rear wheels of course. Block the gas pedal WIDE OPEN, with the engine NOT running, of course. lol Now, adjust the transmission linkage to that it has the throttle lever on the transmission pushed ALL THE WAY BACK as far as it will go. I said to get the car in the air for two reasons. 1) so that you can VERIFY the throttle lever on the transmission is all the way back and 2) because you may need to adjust the linkage "UNDER THERE" as well to get it right.
Once this is done, get the car down and test drive it. IF IT SHIFTS too late and too hard, you should be able to adjust the under hood linkage to allow it to shift sooner. If that's the case, you would be shortening the rod. I always HATE when people throw out "longer or shorter" and then never explain WTH they're talking about or WHY.
If you need further assistance, send me a PM and I can walk you through it on the phone.
