z28camaro1090

I was having issues with my idle surging after further inspection i realized the hose was off the pcv valve on the back of the valve cover. so i put it back my idle went back semi normal but now if i remove the oil cap while the car is running the idle gets really rough and drops.. is this normal?? everything else on the car seems to be working right even seems alittle more responsive since i reconnected the tube. oh and the passenger side is plugged off for some reason too.