check the throttle body, make sure it is not gummed up. When was the last time the air filter was changed, stupid question i know. might be the cats also! the tune could be a little off. That is going to be a hard one. How about the throttle sensor. it could be letting it go down to much at decell.
2004 pontiac gto m12 6sp,polished t/b,160*t/s,pacesetter longtubes,3 1/2"custom single exhaust, t/b bypass,ls7 clutch package, k&n cai, torquer 2 highlift cam 238/248@50-600/605-112lsa,stock #'s 309rwhp,344rwtq, after mods 399.48rwhp,389.52rwtq. 12.70@109 on burned up stock clutch, new mods---ls7 clutch package, new one off paint job,rksport full ram air hood... going to forge the engine and procharge in the near future.