i recently tried chaging my spark plugs in my 85 nissan 300zx. the wrench doesnt grip the plugs and it looks like they are clipped in? i got 2 of them out and changed them and now my car skips so bad it shuts off when its idling. the plugs are gapped correctly and are in tight . the wires are on them tight too. they are the right plugs. any ideas? also this is my second 300zx both of which have leaked oil from a pulley on the bottom of the motor by the oil pan. any easy solution to fixing that?