Fill your car (only to 15 gallon's as shown on the bottle) with premium gas, then pour in a bottle of this techron fuel system cleaner and try to drive the car as rough and aggressive as you can. another way I did it was to merge onto a freeway full throttle to about 100mph then about 80 for a few miles, exited and did it again. I did this 5 time to ensure that this cleaned out the whole fuel system. once I did those runs on my 02 rx300 it purred like a kitten and had no more hesitation. :)