sputters under full throttle

[That SlowPontiac]

ok. im lost on this one. no engine light. runs fine when driving normal. however. under full throttle it sputters after 5k rpm. all 3 coils are sparking no problem so i dont think its icm or coils. ive herd a clogged up cat could cause this but i have a 3in catless down pipe. i put new ngk tr6 plugs on it about 8k miles ago. has anyone ever had this issue before? i have new plugs and wires on there way. if its not that what else could it be?

 

[Fivefingerdeathpunch]

Start with the plugs, one could be cracked.

Or maybe you are losing fuel pressure at high rpm.

 

[Tomtopdog12]

Did you happen to put pre mixed gas in your tank......that can cause it to do that..............:th_lipssealed2:

 

[rickisrad]

If you have access to a scanner look at the individual cylinder misfire count. That will give you an idea of where to look. if you see high misfires on a specific cylinder swap the coil with one of the other ones to see if the misfire follows. also scan for knock