I have a 1993 astro 4.3 V6 - dies at idle and will not restart

I have a 1993 astro 4.3 V6 with throttle body injection (Z vin code). It starts right up and idles perfectly but when it comes up to temp it will die at idle and will not start until it cools down. It then starts right up and repeats. When trying to start it I can see that no fuel is coming from the injectors. I can pour a little gas in the throttle body and it starts up and keeps runing though idle is rough and it kills again. I have replaced the fuel pump the ECM computer, had the injectors flowed( they are fine). No vaccume leaks, no codes and throttle sensor and idle air valve replaced. It will keep running even when hot if I keep the RPMs high enough but will die if brought back to low idle. I am out of ideas - anyone seen this before?