There's coolant in that there hole?

[Aurora40]

I don't know why an external line leaking would cause the car to run rough, though. Have you started it with the hood up to see if you can see it spraying?

FWIW, if you pull the plenum, you may want to take the starter out and give it a good cleaning, get all the coolant out from under it, and dielectric grease up the connections. My starter gave up the ghost shortly after a major coolant spraying incident.