I have a 84 CJ7. It has been converted to a 304v8. It normally runs smooth. However on random occassion it will start running rough, idle will drop and will cut off if I don't keep my foot on the accellerator. I will continue to run like this until I park it. The next time I run it, it will run perfect. It may go 50 miles or a couple of hundred befroe it does it again. Any ideas?

What carb does it have? What's the status of the emission controls?

I would start looking for vacuum leaks first.

I find them by using a pair of plyers to pinch the vacuum line to see if it makes a difference in the idle.

I fixed all the idle problems with my 84 CJ.....I put in a fuel injected 5.7L SBC

And try RRich's propane trick. There's a link to it in the Read This First thread.

Did you upgrade the distributor cap, rotor, plug wires to the 'TeamRush Upgrade' or 'Large Cap Upgrade?

If not, look for a black dust in the distributor cap, and signs on the rotor of cross fire and ground fires...



Two,
Check the metal terminals in the coil connector.
They often give up and don't make clean connections with the coil terminals, and you will wind up with symptoms like this.

Three,
Add a dedicated ground wire to the ignition harness.
The Jeep/Motorcraft factory ignition didn't keep a primary ignition ground very well,
And you should add a dedicated ground wire to the system so it gets ground even when the distributor housing isn't.
(Distributor housing is where the primary ignition circuit gets it's 'Ground')

Splice in a dedicated ground wire to the 'Black' wire,
HARNESS side of the distributor connector.
There will be three wires to/from the distributor,
Violet, Orange and Black.
The black is supposed to ground the system at the distributor, but the distributor isn't the best source of 'Ground'... A dedicated wire to the harness side of that connector will keep your coil and module alive a lot longer.

4. Consider replacing the ignition module.
The Jeep/Motorcraft ignition has a fairly good, but fairly weak module,
And if it's been replaced with the 'Discount Store' brands, then it's pretty close to worthless.

This would also be a good time to clean/fill the connectors with dielectric grease so you keep the corrosion out.

If you have problems with the discount store replacment modules, consider this,
Junk Yard Genius.com 'Stealth HEI Page

5. A better choice would be a CDI, or Capacitive Discharge Ignition module, which would increase usable spark energy 500% minimum, but those modules start at about $130...

6. Another diagnostic tool you might use is a pressure gauge 'T'ed' into your fuel line between fuel filter and carb.
This would let you know if the fuel pressure is dropping when this problem happens.

Something rattling around in the fuel pump, clogging the pick up tube in the tank, or fuel filter clogging would cause the problems you describe, (but it sounds like ignition)

7, Could also be a problem with Fuel, or Carb needle and seat valve, but these are WAY long shots...

The "intermittant" makes it harder to find.

Your plugs - they are the STOCK plugs called out for the ENGINE not the body? The so-called "trick" or "performance" plugs, especially Bosch, Splits or plats, will often do that - they run too hot. When you shut it off and restart they had a chance to cool.