97 acts like it has a vacuum leak but it doesn't

So, I have a 97 GMC K1500. Got it running nice and smooth about a month ago and now it's sputtering.
No CEL
Injectors replaced
MAF Replaced
Full Tune-up
New exhaust (CATS, O2 Sensors, etc.)
Plugs and wires are all connected properly.
I've replaced pretty much everything on this truck and I'm running out of ideas.

Any input is appreciated.