try this. when your gas tank is almost empty (1/4 left) add 3 bottles of Heet gasline antifreeze and a bottle of fuel injector cleaner (optional). Drive hard on the freeway for at least 20 minutes with frequent wide open throttle in 2nd and 3rd (if you WOT in 4th you'll be speeding ). Make sure to hold it above 4000 rpm constantly for a few minutes at a time to get it really hot and to breakup carbon deposits and get them flushed. go immediately to the test station. pick a short line dont let your car cool down at all.

the high alcohol content in the gasline antifreeze will make your car run hotter. but that is what you want. but also don't do this for a prolonged period of time.