I have a 1998 k1500. I left it sitting for 2 days and it would not start. Turns out my plugs wer gas fouled. They had deposits and were wet on all 8 plugs. I cleaned them up and the truck ran fine. After about 3 days it started having the same problem. I’m not to sure what I should test other than the fuel pressure regulator, the fuel return line and maybe the injectors for leaks? Is it possible for all 8 injectors to start leaking at the same time? It has the 5.7L engine in it with the spider injectors. Any help would be greatly appreciated!

 

so it's running rich right. Check mixture related sensors. MAF etc.