there is no point dynoing it for diagnosing a problem at idle, sounds like an air leak or possibly tps switch requires re-setting.
in respose to the above statement .. what a load of crap!!!!!
Dyno's are designed to be used as test/diagnostic equipment.The dyno is not just to run you car up on almost all dynos these days have a/f , load cells, brakes. They were designed for this use long before they were used for tuning. in the early days before load cells and a/f meter we used them as diagnostic only tools. Following are examples of how modern dynos are used and how experienced staff interperate the results not guess ( only examples ) e.g. your car doesnot idle. you would first ask the customer the questions does it idle at all , it is rough , etc. As long as there is some idle all you need to do it put the car on the dyno and put the a/f probe in with the scan tool on. Should the a/f change out of range on slow cruise and drop idle (or 02 voltage be out of spec or heat range). ( faulty 02 ) Should the aac valve over compesate about say 55% open at idle. ( possible vacum leak or pcv open )
With people giving inaccurate and advice like this no wonder mechanics and tuners scratch there head when people come into there workshop blabbing rubbish they read from someone who has never used a dyno.
Dynos , scan tools and product knowledge will cut the cost of diagnostic time down . this also means less wear , less money, and less enviro impact . Just remember its your car. Like i say to all my customers you dont need to listen to me, listen to free advice.. hey if its any good .. they would charge for it.