Engine Probs?

You need to list what you HAVE DONE exactly to improve the situation. It doesn't sound like you've done very much

Frankly the ECU box just might be the LAST of your worries

1 Definately run on fuel from a clean can until you get other things straight.

2 Did you clean /rebuild the carb? This would be no1

3 The dist might be rusted up inside, a few things: The mechanical advance might be sticky, and the reluctor / pickup may be rusty.. Rust is iron and iron is magnetic. This could affect how the reluctor generates spark. Clean or replace. the reluctor and pickup coil. Check and set the "reluctor gap." Check the mechanical advance for free movement, or even consider tearing the dist down and cleaning and lubing the advance mechanism, and check it for wear. Obviously you'll have to reset the timing

4 If it's been sitting "a few years" (they add up) I would just plain automatically replace the plugs, the plug wires, and the cap and rotor. period. End of story.

5 Change the oil, and listen for sticky valves/ lifters. Might want to add some solvent like Rislone before you change the oil and run that for an hour or so.

6 Does it have stock manifolds/ exhaust? Check the heat riser butterfly to be sure it has not rusted shut. Might probe up the exhaust with a flexible stick for hornets (mud) nests, etc.

7 Use a meter and check voltage to the key side of the ignition resistor, then check voltage (running) at the battery. If it's charging, it should be up around 13.5--14.3 or so at the battery. If there is a lot of difference in the two readings, it means you have a VOLTAGE DROP in the harness/ bulkhead connector, and you may be getting low voltage to the ignition system

8 How about intake/ carb manifold leaks? The carb gasket might have deteriorated sitting. take a propane torch UNLIT or some starting fluid and gently squirt around the carb base. If it affects the idle you have a leak.

How do you know it was running any better BEFORE you parked it? Get yourself a compression gauge and a vacuum gauge and Google around on using them.