Excatly, The dual mass flywheel gm used is junk. Sometimes stock but always as soon as you add extra power you will start to get the hard and sticking peddle! The explanation i got from South Bend Clutch is that under the added engine power the two plates of the flywheel will start to separate and the only way the second one can go is back. By this moving back it takes the pressure plate fingers and puts pressure on the throw out bearing. At first its just a little bit causing just the slave to hydrolock. and as it gets worse it will start to slip the clutch because so much pressure is being aplied to the pressure plate fingers that it is just like pushing the peddle in . the only real cure to the problem is a single mass flywheel (SMF) but gm also warrentys the stock one untill 100,000 miles!
Hope this helps,
Caleb