Mr.Whitey

I have been having some problems with a sputtering at partial throttle. It doesn't always do it but other times it gets pretty bad. Most of the time it is noticable but to different degrees. If I got to WOT it seems to run fine. The problem may have some impact on WOT performance but I can't really feel anything and it seems to run smooth. The plugs are only about 3 mo. old and the wires and opti are about 1yr. old. The plugs look fine and the wires seem fine although I didn't remove the wires completely to check them out.
Any ideas what might cause this partial throttle sputtering?
Thanks

TransAmGT94

sounds like a bad opti. does your ses light come on from time to time when it is missing bad?