Had an issue with low idle. Mentioned to Jack that I had changed out my battery just before the issue started. He knew instantly what the likely issue was: the computer that controls the air/fuel mixture had been reset. Who knew the computer actually changes the parameters over time adjusting for deposit buildups. So the factory reset position didn't work well with the dirty condition of this componenet. A quick cleaning took care of the condition. No expensive testing, no trial and error, just a quick inexpensive fix. That is why I have been using Concourse for 25 years.