Fluctuating high idle , backfiring at idle

Hey guys so recently I had a code for my knock sensors, I replaced them and the harness along with the gaskets, fuel injectors (cheep pos ones from advance auto, half aisan half no name. I know I fucked up there)
I replaces my spark plugs from iridium single ground to denso platinum dual ground, and replaced my pcv valve.
I also cleaned my throttle body and iac along with new gaskets for both.
Problem is my truck idles high , around 1000 after it warms up but it also has a slight miss, I can here it backfire at idle pretty slightly .more of a bummed I did all this work for it to run worse kinda thing instead of a performance issue.
But the other thing is after a hard accel rpms will float up and down for 30 seconds from 1000 to 1400 and settle.
When cruising through town suddenly the engine will brake itself intermittently when I let off throttle.
I made sure all my vaccum lines were good.
I did clean my maf with brake kleen like a dipshit
And I'm just curious what your guys first guess would be given my symptoms.
Trucks a 99 3.4 m/t 4x4
260 k miles.
Has had headgaskets 20k miles ago heads were checked for cracks and they checked out good.
Before I did this work my only issue was intermittent powerband above 2000 rpms from knock sensors.
Thanks in advance!