Poping or Misfiring Under Hard Accelearation

[svt2205]

Anyone have any ideas of what I should be looking for? I'm new to the tuner world and have had my Grphyon installed for only a few weeks. First, I'm not entirely sure it's related to the tuner or if it's just my truck.

But under hard accelleration, I'm now getting a poping sound. Sounds just like something has shifted in the bed and banged into the tailgate. That's really what I thought it was, until I noticed it with nothing in the bed.

My truck is an 07 5.4 with 63K on the clock. This occurred yesterday, the second day in a row where we saw wonderfully warm day time temps. Warm being relative, it was in the low 50's. I was running the Gryphon on level 2. I run 87 octane fuel. I looked for codes and it found none. I have since returned to stock and it doesn't do it. I did notice, it had a hard start once since returning to stock.

Let see, what else might be helpful? I just changed my oil (motorcraft 5/20SB and 820S filter (maybe it's S820, not sure which the letter sequence is). My air and fuel filter have less then 2000 miles on them.

I'm out of my league here, so any suggestions would be helpful.

Thanks