you cannot adjust the idle on a 300e...the beauty and the beast of it. it either works or it doesn't....just gonna have to fix things to get it right. the neat thing is, i think, is that the car won't run right unless you can pass emissions and you will know it before the test. i think emissions testing does a favor (for free) for those who drive automobiles that need repair. free diagnostics..that's $100 in savings...you take the failure notice to a mechanic and they will do that to fix it and only that, give you a reciept for this work and you take it back to the testing facility and have it pass. you just got a cheap repair, the repair shops know that they will be called on the carpet if there is something fishy going on ......thank you EPA