Weird clutch issue - 04 VGT

[inthelate80s]

I have a weird one here. I replaced the failing C60 on my 04 GT with a junkyard C60, I also installed an M-Pact clutch kit (yes i know theyre not the best) fast forward a few thousand miles and I decide to send it getting on the highway. i got all the way up to redline basically and push in the clutch to hit 2nd gear and it went straight to the floor. luckily it came back as i was pulling off and i was able to drive home. the clutch was kind of sticking, if i kept the clutch depressed there would be a soft humming noise almost like if your power steering fluid was low and if you slowly let off the clutch th car would move forward as if i was giving it throttle. i thought it was the slave and master so i replaced both of them and bled them properly but the problem still persisted. i figured i hadnt replaced the throwout bearing so it couldve been that. i just got done installing the transmission after replacing the throwout bearing and the problem is still there. could it be because i didnt get my flywheel machined or something or maybe the M pact clutch is defective? i'm not an expert with clutch systems and ive ran out of ideas at this point. i just need the car driving again and would love some help. Thanks!