98 jeep grand cherokee stalls,backfires intermittently

Suggest you check the spark plugs for carbon buildup. this will cause a backfire.

Take the idle air control valve and the EGR valve ogg and clean the carbon out using a non-chlronated brake cleaner

have tour mas sensor checked out

It's not possible to pinpoint, with just online info, what is causing the backfire, but if it blew your muffler open, the engine is definitely dumping raw fuel into the exhaust. Look into what can cause excessive fuel to be dumped into the exhaust and you may find the cause of your problem.

i had a similar problem with a 1998 grand cherokee 4.0 had a no start condition changed the crank sensor the car started idled fine no codes till you drive it then it was giving p0430 p0460 misfire cylinder 4 and 6 and ran rough no speed didnt make sense ran good before sensor went bad removed new crank sensor on the bottom it has a round cardboard glued to it so it does not go in all the way and get caught by the flywheel and break its for the air gap . paper says it will shear off when you start the car problem was it wouldnt let the sensor go in far enough for the proper air gap so when i re-installed the sensor the second time i held it in with left hand tightened the bolt with right hand started the car and it idled fine again but when i drove it it was fine and no codes

Backfiring indicates a timing issue. If you have your wires on correctly, your timing chain has stretched and jumped.

Unlikely that it's a computer. Check your coil and the grounds, make sure you don't have any breaks in the wires that could cause an intermittent problem.

The likely answer to your problem is that you have an intermittent disconnect in the ignition system. If power supply to the ignition system drops out, some fuel still goes through and when power returns it ignites in the exhaust resulting in a backfire. I would look for a bad ignition switch, or other loose connection that could me making/breaking contact intermittently.

I'ts quite possible that your distributor is installed one tooth off and is too far advanced, causing the plug to fire before the intake valves are closed completely. Turn it one tooth counter-clockwise and try it again.

get a couple bottles of gas line antifreeze .. if you don't already use it and add it to the gas.

Robert

P.S. in minus 40 i don't even get out of bed... minus 23 here last nite... isn't winter grand