Ok well I have been having this issue with the stang for a while. I am pretty sure its related to obvious engine mods H/C/I but am curious if a proper tune will help it or not. With the A/C on it will just turn off sometimes. Like I will turn the car on and let it warm up and if I turn the a/c on it will idle fine for a bit then the idle will start to fluctuate and it will eventually turn off. And if I am driving and am using the a/c I will come to a stop sometimes and it will just turn off when I come to a stop with no warning. But if the A/C is off I can drive it all day long no problems. Beat the living crap out of it no problem and idle it forever no problem. I do have a diablosport chip with an off the shelf tune for my cam specs and so forth. But do you think with a proper dyno tune they may be able to take care of this issue for good. Last time I had it on the dyno we actually checked A/f while it was doing the idle fluctuation before it cuts off and it would go from 9:1 idleing like real low up to 18:1 idleing smooth then down to 9:1 and idle goes str8 down and back and forth till it dies. Is there anything I could do either then tune it to fix this?