Gibby

Hi All, I am very new to this--both the car and the forum--, but hope to get some help or advice. I have a datsun 280zx which I love to peices, but recently as I am driving I notice the Tach start to jump all over the place right about the time the car starts to get warmed up, then the car starts to run rough, and dies. It's consistently happening if I rev the engine to high as well. But, I never have a problem starting the car. I have replaced the battery, battery cables, coil, fuel filter, spark plugs, spark plug wires, cap and rotor. Any ideas? Thanks all for any help you can give!! Gibby