need help. engine stumbles.

[p5.0]

Hi All,

1st off here are my mods.
4lb lower pulley
CAI
Flowmaster exhaust
Mafia
SCT tune...

its on 01 L

My symptoms are:
idle seems fine
no CEL
my truck under boost and at 2500rpm starts to stumble and hesitate. I can reach up to 70mph but with out getting on the gas. i dont know if its missing or detination. (dont know the difference)

this is what i have done.
cleaned mass air and filter
changed spark plugs and coils packs seemed fine.
tired reseting the tune
looked for air leaks had 2 from rubber elbows (fixed)
reset mafia

i tried changing out the IAC and when i did that when i reved the engine up the intake made some wierd honing/howling sound. i felt the mass air it was shaking wierd. iunno but when i put back the old IAC it didnt do that.

now im stuck i need help. suggestions.

I was gonna chance my 02 sensors but my CEL has not came on.

thanks

 

[Dusten]

what plugs, and what are they gapped at?
also, if the tune isnt built for the mafia(who tuned the truck?)
if the tune isn't set up for the mafia you're going to run into problems. Also, if the plugs are gapped to wide or just the wrong ones, they'll blow out under load and cause a miss.

 

[p5.0]

the truck has been running fine for over a year with those mods. besides the new spark plugs. the reason why i changed the plugs was due to the problem arising.

 

[Dusten]

well its possible the old plugs caused the issue, what did you gap the new ones too?