Originally Posted by TheOtherDave™

I'm a big fan of Lucas™ Fuel System Cleaner...

But a good substitue is good old "C-12 Chemtool". You'll need a funnel, and you'll have about 4 ounces left over after treating one tankful.

A word of caution: FOLLOW THE DIRECTIONS RELIGOUSLY. If you dump the whole can in there, you risk damaging expensive emissions sensors and possibly the catalytic converter itself. So don't screw around.