I think you mean when the clutch is depressed AND the throttle closed. Then, yes, the revs should drop. But, nowadays, with the emissions being so ****ed up, they program in a "dashpot" effect into the engine control to keep the throttle open when you let off the accelerator pedal. This keeps the revs floating up where you don't want them.
My '12 Mustang was so bad it would chirp the tires if I shifted fast at high RPM's like when I was flogging it on a 2 lane like it was meant to be. It was a lease, so I treated it like a rented mule and just let the thing power shift itself all the time.
Now this might be a little hard to take, so sit down for a moment. Apparently the government has figured out a way to **** up one of life's most simple pleasures, the zen one-ness between man and machine that is formed by the proper execution of gear changes. Let's just hope they don't decide to go after masturbation next.
I don't know if the 07 Tacos had the dashpot effect that pronounced or not. Hopefully some others with personal experience will chime in. It is possible that there could be some kind of malfunction with the throttle linkage if it is not "fly by wire" or that the components that control throttle positon could be screwed up, but my money is on the ****ty parameters they are forced to build cars under these days.
