Missfire under decelleration.

[TXBLU]

My truck has started to missfire while slowing down with the throttle closed. It feels pretty bad sometimes. It might be my imagination, but it seems to run less smooth that it used to down the highway at steady throttle. It still boogies when I mat the throttle, so that's good. :burnout: I am currently running a 4# pulley, K&N panel filter, NGK plugs and the warm tune on the xcalibrator. I will try the cold/towing tune this morning on the way to work to see if there is any difference.

Any ideas on cause?

Thanks.

[L8 APEX]

I only hear that on systems with high scavenge like headers and wild systems. I think it is a lean pop. Check all of your PCV, vacc, brake boost etc lines and the ones under the boot. Maybe it is sucking in unmetered air.

[TXBLU]

I will do that tonight. I also put the cold/tow tune on it and it seemed to be a little better.

Thanks.