FWIW, I dump a bottle of Techron into my tank, 2 or 3 times per year. I've been doing this since buying my '01 new. The fuel injectors have never been touched and now have about 519,000 miles on them.
My engine tends to have a hint of a stumble at idle, but nothing that in any way concerns me given the age/mileage. Apart from all of the other maintenance, I replace the air filter (Toyota) & spark plugs (NGK BKR5EKB-11) every 25,000 miles.
I need to put another shopping list together for my 3rd timing belt job coming up soon.
Andreas