ok so its done this for awhile spark pkugs and wires are new. doesnt do it with ac on. but with ac off it does it engine doesnt rock like its missing but it doesnt make slight pop noise from the exhaust. I do have a glass pack so is that what's causing it? no engine lights or anything and drives good no ill effects except at idle any ideas guys? thanks

Lack of backpressure is doing this. Same thing happens to mine after replacing a rusted muffler with a glasspack

Oh and its not going to hurt anything your just losing low end torque