Coils misfires all sorts of other problems.

So I bought a 2011 2.7l access cab with 261k miles on it lol... the truck is beautiful probably one of the cleanest trucks I've seen in my area with any kind of age on it. The guy I bought it from was sketchy. It was missing when I bought it figured it could be easy enough I work on trucks and my brother is a certified toyota technician right?

So I first do the coils and plugs.. put denso oem plugs but had to settle for autozones duralast coils.
The misfires cleared up for the most part with the random bank 1 cylinder 1 missing on cold cold starts and every now and again.

Vacuum lines weren't connected and all sorts of weird stuff but after I found everything that mysteriously wasnt plugged in I checked for Vacuum leaks and found none after searching for hours.

My biggest thing is rough idle when I come to a stop, poor acceleration and loss of power.. and a rattling sound while I accelerate plus it just sounds weird! Sounds like air is being pushed from the intake manifold side with ticking like it's got an exhaust manifold leak??
The exhaust system itself cat back has leaks EVERYWHERE. Tried the epoxy and it was a waste of time but when it did hold for the 20 mins my truck was night and day difference! Sounded like a truck again it had power... well as much power as that turd 4 cylinder can push.. fuel economy went back up even.

I guess what I'm asking is can an exhaust leak cause this many issues? Anyone have tips on these high mileage 2.7s?

I've ran coolant pressure tests and a combustion gas test for head gasket and negative on both.. I haven't checked cylinder compression or bore scoped in there but I know coolant isn't leaking but maybe the rings are worn? I'm thinking of that was the case plugging the exhaust for a bit wouldn't help gain power again...? It does consume some oil though..
I'm all over the place someone help please