Running fine last week, this week won't even idle

[XavierBK]

Any ideas what would cause my truck to go from running perfectly fine one week to not even being able to idle the next? It seems like the truck has developed a nasty miss. What I don't understand is I've run the truck with three plugs unplugged before by accident and, while it idled rough, it still idled. In its current state the thing won't even idle.

There is also a noticeable hesitation when the accelerator is given a quick push. Sometimes it almost bogs out from that alone.

[breadbox]

Vacuum leak makes the z24 idle like poop. Start there. Too thick of a coolant mix also seems to make the z24 unhappy, at least in my experience.

Also pull some plugs and look in the 720 info thread, I posted a guide to spark plugs and what different things mean.

A bad/loose ground will also cause hesitation.

[XavierBK]

I poked around this morning and noticed an open vacuum port. It stood out because I deleted and capped everything.

Not sure how the cap came off but I put a new one on it, with a hose clamp this time, and it runs fine again.