JD 3020 shutdown

Need some help in analyzing a problem with my 1965 John Deere 3020 gasser. A couple of weeks ago I was picking up bales with my 3020 and a New Holland 1033 stackliner. I was going up a steep hill picking up a bale with over 100 bales on the Stackliner. I was in 5th gear and it was pulling great (stout tractor) and suddenly it sort of coughed and died. Lost brakes and steering but I was able to get it into park before it started to go backwards. It restarted ok and I put it into 4th and finished going up the hill although it was running rough. After dumping the load in the barn it worked fine the rest of the day. This week I was using it again for raking and it worked fine for a couple of hours and suddenly it sputtered some and finally in a turn it completely shut down. Left it sitting over the night and it started in the morning but sputtered all the way to the shop. Now it won't start at all. This tractor has an aftermarket electronic ignition about 8-10 years old. I checked the coil with an ohm meter and it appeared fine. Have spark so I know the distributor is working but no sure if spark is up to snuff. I have heard electronic modules either work or don't but I don't know how to test them. Fuel pump tested out at about 5 psi and I sprayed some ether in the air cleaner (oil at proper level) but it wouldn't start but it did slightly cough one time. Going to have the high energy coil tested at O'Reilly's to be sure. May take the carb off later to see what is going on there. If I don't find something soon will check timing and compression. This has been a bullet proof tractor that I can always count on to start and work without any problems, doesn't use a drop of oil. Any thoughts on where to proceed? Been a rough week with 3 vehicles with AC problems, two tractors on the fritz, guy wired my paint booth exhaust fan backwards, and we haven't had any rain for over a month and none in sight.

Use a spark tester or a spare sparkplug with the gap bent open to 3/16" to check for spark. If it jumps that, spark isn't the issue.

If it coughed and stalled, then ran again, you can pretty much rule out timing and compression, 'caus they don't do away, then come back for a while, then mess up again.

My guess (after weak spark) would be water or debris rolling around in the bottom of the carburetor.

A floating inlet or outlet valve in the fuel pump can cause your problem. After it stops and the valve settles back in its seat it works again for a while.

I had that problem on the 4020 gas. Checked some things out didn't find nothing. Knew the pump was old so I took a chance on it. What are they like $40 or 50 dollars ? Turned out that was the problem.
Mine was running GREAT until I ran it out of gas or about out I thought ? After a refill it would not restart and / or acted weird .

In addition to other posts drain sump on
bottom of fuel tank. Probably not your
problem but easy and free.

Thanks for all great inputs. I think I will replace the fuel pump first as I already did the spark plug test. Great idea on draining the bottom of the fuel tank also. I'll let you know what fixed the problem when I get er done. Got company right now and tied up helping out the wife entertaining and feeding the folks.

Sounds like spark plugs, they will do that if your piddling around and then they wont pull the load .