1984 Nissan 720 4x4 starts fine but runs rich, misses, sputters. New distributor, plugs, wires, cleaned fuel tank.

This sounds exactly like a bad fuel pump. Do this turn the switch on then listen for the pump to run when it doesn't run have someone beat on the fuel tank with a piece of wood if the pump runs replace it. I hope this helps. Take Care.

Pull out the spark plugs to see their condition, if they look fine check the resistance on the wires and make sure the distributor(if it has one) is fine too. Another thing too it can be a fuel injector that went bad

Does it use spark plug wires or individual ignition coils for the each plug?. My 98 intrepid uses coils and occasionally I have to change them out cause it would start to miss when normal temperature was achieved. If it uses wires, try replacing them, along with the spark plugs.

I used to own a older datsun pickup that had similar problem. The solution I found that fixed the problem was the points and condenser had grounded out when the engine reached high enough temp. replaced them and set gap a little tight to compensate for the expansion.

Sounds like plugged catalytic converter, Disconnect exhaust in front of Cat. and see what happens. Check to see if you are losing fluid from radiator.

38 psi is high ??? MMmmm ..regulator... but you need spark check the coil make those plugs arc see them flash ....advance the distributor a lil just a inch ...

I don't think an exhaust leak would cause the sputtering in all gears. I've run my Geo in the past with a cracked exhaust manifold for months, and it ran fine, just a bit louder. Are your spark plugs & wires in good shape (missing vs sputtering)? Also check inside the distributor cap for corrosion/carbon build up. If all that is ok, then I would start with the basics: first try running a complete fuel system cleaner through it for the next two tanks, that should clear any partially clogged fuel injectors. If no luck, then replace the fuel filter, and try it, if it still sputters you can check the fuel pump strainer if it looks ok, then you might want to replace the fuel pump.

if you have an electric fuel pump that would explain the hum. unhook your incoming fuel line and blow the line clear, sounds like you've got some junk in your tank.it'll build up on the screen in the tank then fall off (at least partially) when your making turns or hitting bumps or holes. next time it's only got a gallon or so of fuel i'd drop the tank and check the pickup tube inside. sux but that's the only way to get to it. while you've got the tank off and out from under the jeep, might as well clean it out real good and replace anything inside (usually the screen) that doesn't look right, dirty etc. wouldn't hurt to run a bottle of fuel system cleaner in the next full tank of fuel either. preferably as soon as you put your tank back. good luck

Run a Couple of cans of B12 Chemtool through the gas Tank 1 Can ata Time on a Full tanl of gas. This will Clean the Entire Fuel System and is the Best that you can use. If this does not work, Let me know so that we can start Checking the Ignition system, Plugs, Wires and Distributor. The first Solution is the Cheapers though.