Hi I picked up a 79 280zx the car runs great then about 30-40 mins into driving it starts running really rich and you cant go anywhere if I rev the motor to 3200 rpms I can get the car to go if it falls below you have to catch a sweet spot with the pedal a little over 1/4 throttle it seems to smooth out but if you give it more it starts popping and wanting to die if you shut the car off let it cool down it will start and run fine until its warm or that 30- to 40 min mark I also noticed the idle when your driving and come to a stop push the clutch in the motor stays at 1700 rpms for 5 plus seconds then drops to 600 rpms I dont know if thats right ive never had or been in a 280 any help would be great I just dont want to start putting parts in for no reason Thanks

Hi,

 

The description above won't help pinpoint, the best thing to do is to start running diagnostic tests. 

 

Maybe this will help:  http://xenons130.com/files/1979%20280zx%20FSM.zip

 

It's probably the ignition control module more than likely.