I have a 1981 280zx non turbo inline 6 that starts and idles good. After a few minutes of idle the engine will start missing and running rough. It will eventually cut-off. It will start back eventually and it seems to be flooding. The spark plugs are smotty (new plugs and wires installed). I have changed the CTS between cylinder 5 and 6, checked all the injector signals and cleaned the Mass Air flow sensor. The fuel pump is a brand new Nissan pump that is producing 30 psi during this condition before the pressure regulator. I have installed a new fuel filter and also temporarily removed the catalytic convertor and the problem still exists. It seems to lack power at acceleration all the time. Any ideas will be greatly appreciated.