1994 jeep wrangler backfiring missing,

run the fault codes
check ignition timing is not too far advanced
have a compression test done to check for valve seat insert loose.

run the fault codes. check the serviceability of the cat converter as it may be broken inside and blocking the exhaust

Diagnostic Trouble Codes - 1993
Jeep

11 IGN reference signal. 13 Fault in the map sensor pneumatic circuit. 14 Fault in the map sensor electrical circuit. 15 Fault in the vehicle speed sensor circuit.

Hi, can you tell me which exact trouble code you are getting? The relevant circuits are below.

1994 Wrangler with 200,000 miles on the odometer. Similar problem here: Severe bucking and backfiring, and engine misses when traveling down the road. I did an entire tune-up (plugs, wires, distributor, distributor cap, and ignition coil), but got the same thing. I thought it was dirty fuel injectors, so, I poured a bottle in a few times on fill-ups. The final solution, was a bad alternator. My mechanic said it was sending voltage spikes to the computer, causing the engine bucking and back-firing problems.

The ECU controls all of that. When they start to go bad they do very strange things that are hard to diagnose. They run about $300 bucks of you do it yourself. They are simple to do. Shop around because it is an electrical component and many places wont warranty them but some places do if your lucky you can find one. I also would not rule out your timing or distributor. I dont know you or what you have checked but could be the rotor or could be carbon tracking inside the distributor. Even the slightest crack in the cap can mess everthing up.

Start with the basics...meaning check the spark plug wires and spark plugs. While under the hood, inspect all hoses for a vacuum leak(s). Then turn the ignition key on-off-on-off- on...leave in the on position and write down the number of flashes the check engine light indicates....2 flashes = #2....pause.....3 flashes = #3.
Let start from here. Are you able to perform engine repairs or diagnostics???

is it the straight six? if so first disconnect the battery then there should be 2 bolt 13 or 14 mm. take wires off. then reverse for install.

'till you do some in depth testing of all systems, I'd place equal weight on every possibility. Make sure you cover the basics like fuel filter etc before getting crazy with it though. Also check cap. rotor, coil and wires. Idle cylinder pressure is different than that encountered when driving. This additional pressure will cause ignition spark to seek a better easier ground,(not the spark plugs where it should be going) causing missing under load.After checking , if you haven't found anything, its time to begin testing fuel pump pressures, modules and controls.
good luck

Fairly common problem. Typical scenario is start vehicle, runs fine for 15 to 30 seconds and begins to backfire when placed under load as customer tries to drive vehicle. Flooring usually makes the problem go away. Usually does not throw a code.

Fix is to replace the upstream 02 sensor.