84 ram charger won't start-help!

going crazy with electrical problem on ramcharger. It's 4-wheel drive with a318 engine . have had in shop after no start(break-down}
after a lot of checking they checked ECU . It tested good, they cleaned where attaches to fire wall and put in one new bolt. It STARTED!
Drove 10 miles home ok, started it next morning but didn't drive anywhere. the following day NOTHING! Turns over fine but no spark to plugs. checked coil wire-no spark to dist. off coil wire .This is where I am at now . the parts I have Replaced are coil, p-up coil,dist.cap and rotor, new plugs, wires are about 1 year old but look good . I have tested pins and sockets on ECU and followed troubleshooting guide for this make. I did get ressistance with ohms check on ECU pins 4 and5.
Book says this could possibly be short or open wire between ECU and coil
I hate to get into harness {main wire set-up} if I don't have to. It seems to be in pretty good shape. I am going to check voltage on coil now . Why no spark from coil? any suggstions would be of great appreciation. I am new here and it seems like a good site. thanks toany who can help! "fire"