WHY DOES MY1998 INFINITY Q45 RUNS PERFECT BUT KILLS AFTER IDLING FOR ABOUT 20 MINUTES. RESTARTS BUT BLOWS BLACK SMOKE OUT?

SOURCE: 1998 Infinity Q45

Hi, i would replace the air filter, make sure the air hose from the air filter to the intake is not kinked or blocked and check for vacuum leaks. If these are all fine, I would check the fuel pressure as it is possible the pump is weak and not supplying enough fuel.

SOURCE: why does my 1998 infinity q45 kills after idling for about 20 minutes, it will restart but blows out black smoke?

Black smoke means that it has gotten too much fuel from the intake. That is a sign that either the timing or valves are having issues. It could also be that the crank sensor is failing. The sensor controls the pulses to the ignition. There is also a cam sensor that might be having issues. It is curious that it is happening at idle. One of the causes could be heat.