there is a great reason that your TB is pretty clean and didnt need anything.
There arent that many miles on the car (from what i know about yours--2004 MY) and as such the filtering offered by the OEM filter or even a K&N really does not allow for a lot of grit to enter the engine.
Really TB cleanings fluids were designed for cars that started to use TB back in the day when filtering elements were not nearly as good as they are today...more when they were like those crappy fiberglass $0.50 AC filters that alot of apartments use. Also they are for engines that are run in very dirty conditions or have little filtering before the intake plenum (ala race cars) and need the absolute maximum power.
A TR4 isnt a great canidate for TB cleaning unless you have like 100K miles on the clock or more.