I have a 1985 244DL. On a rainy afternoon a couple of weeks ago it refused to start after work. It would crank and sounded like it wanted to start, however, it just wouldn't fire up. I figured it might be a moisture problem and decided to see what would happen the next day.
The weather cleared up over night but it still wouldn't start in the morning. By noon, it started fine and ran normally.
A day or two later I was driving on the highway and it just quit. I pulled over and tried to start it and again it cranked but would fire up. I checked the plug wires at the distributor and the ignition coil to see if all were tight and then tried starting. It started and ran normally.
A few days later it was running funny and wouldn't start after turning it off. It did start again a few hours later.
I have checked all the fuses I can find. After getting coated in 20 year of grime that was stacked all over the engine, I washed the engine. (creating more problems? - possibly) I have replaced the distributor cap, plugs and the ignition coil. Didn't help.
I suspected fuel pump relay. Both the main fuel pump and the in-tank pump turn on when connecting jumper wires so I know they work. I checked power to the in-tank pump at the connection close to the pump and it gets power when starting the engine. I can also hear the main pump run. So, I assume it is not the relay or pumps.
The car now starts but runs very rough. The whole engine rocks.
I don't know where to look and I am not a mechanic. I still don't know if the problem is fuel related or electrical.
Does anybody have any ideas before I give up and find a repair shop.?

How are the wires in the engine compartment? Since 85 is in the range of years with bad wires, I would suspect that. Did the really rough running start just after you washed the engine? If you remove the AMM connection (engine off), does that affect how the engine runs? Be careful putting the connector back on (again with engine off) not to damage the pins, and look for moisture there. How about the wires going into the distributor? An intermittent short there could be a problem.

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'81 GLT 245 W/245K; '83 DL 175K

The plug wires look in good shape. I replaced the plugs already. I am not a plug expert but I thought when I took them out that they looked black.

I have filled up since the beginning of the problem so I don't think gas is the problem. Also, if the current problem was the only problem that I have had I might think more gas related. However, would bad gas cause such starting inconsistencies and a complete momentary shutdown?

I know you've been over the plugs, wires, cap and rotor several times because that is the obvious suspect for your symptoms given the story of how it all came about. Look carefully again for a difference in appearance at the plugs. Test suspect cylinders by grounding the cylinder's wire at the distributor cap. Lift the boots high first so you can poke in a ground wire. Don't rule out the cap just because it is "new". Moisture can put a track in a new cap as quickly as in an old one.

You mentioned the plug/coil wires, if they are old, replace them. Pull the plugs to see if it is fuel/electrical problem. Wet says electrical, black says timing, totally dry says no gasoline.

Klaus
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98 V70Rawd(101Kmi), 95 854T(85K mi), 75 164E(173K mi)

I replaced the plugs and the wires look in good condition.

I peaked at the timing belt and it also looks in good condition. Is there a way it could it have lost the timing without the belt slipping?

The timeing change could have been caused by turning the distributer a degree or two. You didn't put the cap on 180? did you? No, I didn't think so. Besides, this problem started before you messed with the wires, etc.
Check all of the wire connectors for the sensors, especially cold start wiring.

Klaus
--
98 V70Rawd(101Kmi), 95 854T(85K mi), 75 164E(173K mi)

Could it be bad fuel? Did you fill up just before these problems started?

I don't think it is the fuel. It was running normally on this tank.