1993 GMC C2500 HELP

I have the identical van I hauled my carpets cleaner in, subsequently, I experienced the same problem that you are experiencing, I had a bad fuel pump that was given the low pressure and giving me the same symptoms that you are describing, I went ahead the same time and rebuilt the throttle body, to make sure I had no vacuum leaks, which also causes the same symptoms, the kit to rebuild the throttle body runs about $20, the fuel pump is about $45, and you will have to remove the fuel tank to change the fuel pump. You can check the fuel pressure, if you wish to make sure it is the pump, but you can only check it at the fuel filter. Good luck.