I had the same problem with the ACT clutch it didn't go away untill the clutch killed itself from clutch drag. I even did steel braided clutch cables, forged clutch fork, and high temp clutch fluid. Something that helped out a lot though was getting a solid shifter mount. Their like 30 dollars online and a lot of work but worth it. If its anything like this video. Now im running the exedy stage 2 clutch and its holding up to my 400-450hp.
If it is like that just get ready for winter because it gets worse in the cold.