Why does it start on ether but will not run without it?

It is not a good idea to use ether on a diesel engine. With that in mind you have an issue with the oil pressure in the lubrication system or an injector seal that is bad.

Do not use Ether on that engine!!!!!!!!!!
Right now the carbs are gummed up and need cleaned. Ether can blow your motor. You can get some throttle body cleaner or take it in and have carbs cleaned.
Just don't use ether

Fuel filter?..or vac acctivated fuel regulator..check w/ vac pump...is new pump running do you hear it relay clicking ????

the problem with the 6.0 it could be many things and is very hard to tell what it is without an enhanced code reader.maybe glow plug system if you ether it and stays running. or egr stuck open, or the oil pressure sending unit (high pressure system) good luck

There are two areas to check for this problem. The fuel and the spark. There is a Timer for your Glowplugs and you should hear clicking and notice the lights dimming in Synch with the clicking. This should work with your "Start" lamp in the dash.

Test one or two Glowplug wires with a Testlight and see what kind of Spark you have. If the spark is present you need to pull about half of your Glowplugs, if not all, and Test them with Battery voltage. They should be uniform in glowing and be careful not to melt them. Any Glowplug that remains cold or sluggish should be replaced. If no Spark, then check the Timer or replace it. Some models may have a Relay, check with Autozone or Oreillys or similar for parts listing.

The Glowplugs start a cold engine. In a warm engine, the Timer will not engage at a certain temperature. Engine compression will ignite the Ether if the Glowplugs do not work, but compression will not ignite a cold diesel engine.

Fuel, if you have a bleeddown in the fuel system the pump may be weak or there is a hole in the line or bad "O" rings. The Ether simply gets the engine turning fast enough to siphon the fuel and draw it back to the pump. A shop can pressure check the fuel system for leaks or use a "smoker machine" for difficult to find leaks.

I hope this helps and you are happy with the info I provided.

To fix the high idle, replace the top oxygen sensor. I would drop the transmission pan and change the transmission filter. You can then check the old fluid for contamination and metal filings. Metal filings will clog the transmission filter and lead to low pressure that would cause delayed shifts

if diesel it is caused by low compression, rebuild it or live with it
if gas you may have a air leak, vaccum line open, or choke not operating

does it start easy after it is at operating temperature
??

first go to an auto partstore and have the code checked. most do it for free. could be coil, fuel pump, fuel filter, air filter or even a bad gas cap. but the dianogstic test should pin point the problem.

sdada

check the crank sensor