Missing First, then Loss of Power, Decreased Mileage & Idle Stumble

Hello Everyone,

I have a '99 Taco, 3.4L V6, Auto. 235k Miles.

Several months ago, I started getting CEL and OBD-II tool says random miss on cyl's 2 and 5. I swapped the coil packs with another cylinder, since these cylinders are served by a single coil pack.The miss remained on 2&5 (no change). So not the coil pack, I guess. I never noticed any change in power or even felt the miss. The miss comes consistently upon reaching about 73 MPH. This has been going on for about 6 months.

Recently, and this may or my not be related to the miss, I noticed a ticking. Maybe 8 ticks/second at idle (~800 RPM's). Subsequent to noticing the ticking, I've found that I have a loss of power - most notably at lower RPM's and when the engine is cold - and mileage has gone from ~18-19 MPG hwy to ~15-16 MPG Hwy. Also, idle has gotten very rough/stumbling. Video with sound of engine, below:




I've looked for open vacuum circuit, but don't see any. New Toyota plug wires about two years ago..

Looking for thoughts on potential causes of miss, tick, loss of power & mileage.
Where to begin? I recognize these issues may or may not be related.

Thanks! Any serious input, greatly appreciated.

 

Bumping this to the top. Hoping someone has some insights that may shed some light on one or more of the issues I've detailed.

Thanks again