Cleaners like Berryman's work great on cars with carburetors and even those with injectors suffer build-up in manifolds and throttle plate which can reduce mileage and smoothness. There is even a post here about removing the intake manifold to get things really clean and those pictures show the gunk.
Keep in mind that in-line injector cleaner solvent delivery systems do a much better job cleaning injectors themselves but this is pro-stuff. But a bottle of Chevron Techron injector cleaner in the tank actually can help. Anything Lucas is a product you can believe in as is Berryman. IMHO STP is a marketing name only for mild home-owner grades.
