Ok i got this Del Sol with a GSR swap and a LS trans a couple months ago. I love it but its been giving me a different problem to troubleshoot/fix every 2 -3 weeks lol. so far ive been lucky and figured them all out, they have all been minor but headaches to find. Soo it seems it has givin me another problem this week and im not %100 percent on what to do or where to start but have some idea.

It would always grind when shifting into 2nd and 3rd gear mostly at high RPM but more recently it was noticeable at low RPM. (If i physically slammed the clutch to the floor with my foot hard it seemed to shift a lot smoother) then last week it was acting funny harder to put in gear at times and then the last day it was even popping out of gear. then on my way home from somewhere i was driving normally put it in 3rd then when i released the clutch it acted like it was in neutral. so i pushed the clutch down and tried again, same thing. so then i tried putting it in 4th to see if the gear was there and it wasn't. the shifter can smoothly go through gears but car acts like its in neutral. there was no pop, grind, or any type of sound or movement from the car.
So with that said any ideas?? trans clutch or something else?

i have a spare GSR trans at my house but i don't know if it is good or not the shaft spins smoothly and freely but that's about all i tested.

sorry so long and thanks for input in advance