Rough idle and won't stay running

I have a 1998 Chevy 3500 5.7 L vortec.
Today I lost power. Would give it gas and it
would barely go. Trying to die. Almost like no
fuel pressure. But also acting like the
exhaust was clogged. My boss said it was
probably the catylitic converters. So I drilled
them and cleaned them out. Still the same
problem. It will start but won't stay running,
running very rough with giving it gas and
won't get over about 1000 rpm. I think the
problem could be a fuel issue but checked
the valve on the fuel line. Had good pressure
it sees. But I don't have a gauge to check it
with. It had been running rough when it first
started, for about a month, but if I just let it
idle for a couple of minutes it would then
idle fine and run good. But then this
happened today