My check engine light began blinking at start up the other day, indicative of detonation. Plugged a reader in and it popped up that my 5th cyl is misfiring.

Wires checked out alright. Plugs have no sign of fouling or detonation. Also doesn't feel like im losing compression, but with a v6 it can be hard to tell.

Usually detonation+misfiring = coolant problem, which I have (small leak, as of yet unlocatable).

Anyone ever encounter this problem? Any advice?
I'm doing a compression check tomorrow just to rule that out (crosses fingers).

I'm trying to not have to take it in anywhere and get reamed with high repair costs, so any suggestions as to what it could be would be helpful.