Backfire at high RPM while accelerating & taking longer to start

[DjSoundScan]

Hello I have a '03 TJ 4.0 with 225000km (almost 140000miles).
Lately i've been having some intermediate backfiring issues. It did it a few times while accelerating getting on the highway in 2nd or 3rd gear close to 3000rpm. Wondering what can cause that.
It's done it before but only when in 5th gear slowing down going up a steep hill and when the RPM gets really low and try to force it or leave on cruise mode so i don't down shift, but once that happens i have no choice, but never at high revs. its done the low rev backfiring even when bone stock.
Also for a few days now its taking too long for the engine to turn over at the cold start. once its warm, it starts in one turn.

Sparks plugs are 40000km old Champions
4 hole injectors (remanufactured by Ksuspensionfab.com)
DEI fuel rail and injector heat shield
K&n Intake
62mm throttle body
throttle body spacer
Cat back dynomax exhaust
91 octane fuel
2 engine oil catch cans.
running 33s with 4.56 gearing with a nv3550 tranny
stock cats

 

[dbbd1]

Is it backfiring (can you hear it or feel it) or more like "bucking," like you're hitting the rev limiter?

 

[DjSoundScan]

u can say its like bucking. its not a loud explosion, its like a can exploding i guess... theres a slight loss of power for that fraction of the second and then its riding normally.

 

[greenjeepthing]

Pure guess is fuel filter. Clogged or dirty Fuel filter has caused both of those complaints before.