300Z missing after it warms up

A friend of mine has a '91 300Z. A water line broke and the car ran hot, but wasn't run long. They fixed tne hose and now the car misses after it gets to operating temperature. They have changed the coil and plug on the cylinder that is missing, but has made no difference. He talk to another mechanic and he said it could have a cracked head. Any suggestions will be appreciated.

Try ohm checking the fuel injector on that cylinder. If you have the equipment do a compression test.

Doubtful its a cracked head... possible blown gasket. But do as Broke said.