Whats wrong with car tranny or clutch??

I have a 98 cobra with centerforce dual friction clutch, steeda adjustable cable, firewall and double hook quadrant, My problem is that my car doesn't want to go into gear sometimes and sometimes it doesn't want to come out of gear. I have tried every adjustment but still have problems. I have adjusted the cable out until my clutch would actually slip and it still did not want to go into gear, seems like when I am rolling it goes into gear fine but when I am stoped sometimes I have to cut the car off to get it back in gear What could this be???