Your motor is stock, right???
Knocking/ticking is always hard to lock down. We always tend to think lifter, but sometimes it's not. Still, it IS
a textbook prerequisite to a lifter failure, which is why it is so highly anticipated. Plus, your misfires started after this prerequisite, which points more to mechanical failure. You'd need to physically rule this out, and it may mean a 2nd opinion locally.
Before that 2nd Op, if it is still making the noise now, get yourself a stethoscope if you don't have one and find the location of the ticking noise.
There are a few ticks that could result in poor mixture or erroneous mixture calculation.
Exhaust Manifold Leaks (tick tick tick) result in a false lean, which causes the computer to dump fuel into the motor thinking it needs more. That causes excessive fuel and causes the misfire if the false lean is bad enough. Would be interested to see what LTFT and STFT says. Those MLS manifold gaskets would make such a sound if exhaust is allowed to pass through.
Injectors can tick as well if overly clogged, but that usually means less fuel. Still, a leaky injector with a poor spray pattern wouldn't allow for a proper combustion event, and it too would cause a misfire and could also show up with excessive fuel after the valve is already closed.
Excessive vacuum leak (may not qualify as a "tick tick tick"
). That would let air into #6 if it was an intake manifold gasket, though it doesn't mean another air leak can't be the cause. It may just be biased on #6 if
it isn't mechanical.
Finally, there's the lifter tick. If this is confirmed, you already know what you'd need to do.... At idle the lifter tick is usually most perceptible, and it would be around 5 times per second on average if your motor is stock. (Counting 600RPM / 2 Rotations = 300 / 60sec = 5 events per second)
These are suggestions, but I've no idea how accurate. I figured I'd throw a bunch of darts up for you to consider. It sounds like it is mechanical, but I can't really intelligently draw that conclusion from here with confidence.
I hope I've given you some angles to consider.