Ok, so here's the problem- As I'm driving along it seems to be fine. But if I'm stopped my truck (1996 c1500 5.7) will have a really low idle. Sometimes when I start it it does it, too. I find that shifting to neutral when I'm at a red light helps sometimes cause it'll speed the motor up just a little bit. But sometimes it sounds like it's about to just shut off and gets low enough to kind of sputter, like it's running out of gas. Any ideas?

 

How many miles on that engine?
Do a compression test, cylinder leak down test and
Vacuum test, post the results and you'll likely get a lot of
help on what is needed. Most auto parts stores loan the tools
For these tests free. Good luck to ya!