Troubleshooting help needed!

Okay..first off sorry that this is basically another post about the same issue (not sure how to delete the other one), but I think I may be able to lay out what’s going on a little more easy to follow rather than keep adding to the original. Also, thanks to those who have helped diagnose my issue.
Vehicle: 99 tacoma 4x4 2.7L
A little history that may help or not? The past year or so I’d get a little engine squeal when starting up, which would go away after a few minutes…mostly during colder months (also accompanied by slight tapping which would also go away). Also, I noticed a drop off in gas mileage over the past 2 months…..
So currently, I have a misfire problem in cylinder 4. When the problem arose, my truck began sputtering with severe loss of power and flashing check engine light (which came and went during the ~10 mile drive home). After limping home, which I now realize maybe I shouldn’t have, I saw that my cat was glowing orange (hopefully not toasted). I understand that this is likely due to the unburnt fuel getting there. So after getting an OBDii reader, and seeing that it was a misfire in cylinder 4, and sure enough that plug was very black and sooty. I changed all the plugs (not wires though). After starting up with new plugs, it seemed to be running normally. I did not drive it, but did rev up the rpm’s and everything seemed okay. Well besides some smoke coming out of flange on engine side of cat (likely due to burning it up?). There was what seems like normal pressure coming out of exhaust pipe (so not clogged I guess?).
So I thought I had the problem figured out. Well the next morning, after jumping off the truck (battery died due to leaving key in ignition), it started up and began idling very rough, and squealing loudly (same sound I’d here occasionally during start-up; a belt?). Also, had the same original problems: shaking, loss of power. I rechecked the computer even though the check engine light never came back on. It did show cylinder 4 misfire code again, but I am not 100% positive that I cleared it the day before (99% sure, but not 100). So I cleared that and restarted for a little while, and could not get the code to come back.. although it is still idling badly/squealling. So this now constant squealing has me pretty concerned..could whatever this is be the source of my misfire issue? Bad water pump?
So my next steps are to change out the spark plug wires, then maybe ignition coils (have 2). What else can I look at? Injectors, MAF sensor? I’m realling trying to avoid towing to a shop (can’t really afford right now). I’d like to at least get some troubleshooting done.

One more thing...my truck has ~ 165,000 miles so I'm sure that it is do for some maintenance.

Thanks in advance!

 

Quick update..turns out that it may have been the spark plug wires..running like normal now with both plugs/wires. Still a little squeal at start up that i need to look into, but at least i can get around now!!

 

That little squeal is likely a slightly loose drive belt. Check each one, and tighten up the one that is loosest.