Tom and Ray from Car Talk recommended Chevron Techron in one of their columns. I throw a bottle in my cars once a year or so. My mechanic has a “Motorvac” fuel system service that supposed to clean the fuel system, injectors, valves, etc.
http://www.motorvac.com/specs/CarbonClean_MCS245.pdf
The service runs about $100 - 120. There’s fairly divided opinions on the usefulness of these types of fuel system cleaning services, but I have it done on every 40k as preventive maintenance.
Ed B.