the car is d16a6 turbo. i tuned it on zdyne. until a few days ago it was runing normal.. but lately at only about 20% throttle the car will sputter or buck once in a while.. not always either.. i re checked my tune and its fine. i changed plugs and cap and rotor is new.. i even changed headgasket to be safe and still the same.. i rebuilt the motor about 1000 miles ago.. never had a problem.. at full throttle its perfect. boosting 15 psi and it runs fine.. just cruisin it has a random miss.. any idea? timing is setr to 16* and belt is dead on.. i also changed fuel filter.

 

What the changes in air temps at your city? I know you say its not the tube but If it gets to cold and your car was tuned in warmer months for lean cruising AF's, then it might be leaning out a little. It may very well not be the problem but just another idea of something to check.

 

i street tuned it myself. i re did my tune just yesterday too to make sure.. its like 19* out in PA at night.. when i pull my plugs they look pretty rich .but it def shouldnt be leanin out

 

i dont run an o2. i only use it for tuning .. the tps should be good.. i changed it not too long ago and im not getting a code for it.

 

turns out to be my tune somehow got too rich.. i turned boost fuel comp % from 180 to 175 and its better now.. plugs dont look as rich and it dont sputter at lower rpms .