I used to work for a major oil company and was responsible for the national distribution of the detergent additive that was added to the gasoline when the tank trucks were loaded for delivery to the retail gas stations.
All gasoline sold since about 1993 has to have some amount of a fuel injection cleaner added to it. The better know brands have more added as well as the higher octanes. IF you use brand name gasolines and put the higher octane in it as well you'll doing about as much as you need to do. The one major brand of fuel injection cleaner you can buy is made by Chevron, called Tectron. It is usually the most expensive but you get what you pay for.
The reason I think it the best is Chevron makes gasoling detergent additives for many gasoline marketers. I know the company I worked for bought it from them.
The worst thing you can do to your fuel injectors is to take many short trips. Each time you stop a small amount of fuel is left on the tip of the injector and in the intake passage as well as inside some of the cylinders that haven't had the intake close when you shut off the engine. The fuel turns in to a vapor and then condenses onto anything that is cooler. The back of the throttle plate is a favorite place and the injectors as well as the fuel still in them will cause them to cool faster then the intake manifold. This fuel condenses and then later evaporates leaving deposits that cause the problems.
'00' SVT Contour
'87' VW ITA 16V Scirocco race car
"Drag racing is for those drivers who can't brake and downshift at the same time."