stalling

I have a 91 cherokee limited, pretty much stock except changed to a dynamax muffler. sometimes while driving it will start to stall, but if i rev the engine to around 5000 rpm it will backfire and run fine. its almost feel like there is something clogging up the engine and it spits it out. it doesnt do it all the time, just when it wants.

i have tested the fuel system, doesnt make any codes. cant figure out what it is. not the cat either, its hollow, and did it before it was hallowed out.

any help would be gladly accepted.

check egr valve, and solanoid, not much info to go on, also may want to buy two cans of throttle body cleaner , spay in the mouth and clean good with a tooth brush.

when did this vehicle have a tune up last?