318 issue randomly..

Ok, Ive never owned a gasoline powered vehicle before, I work on em at my shop just never owned and operated one. Always diesel. So trouble shooting non OBD2 type vehicles isnt my strong point.

'71 dart, 3.91 rear gear 904 auto. 318 with std 360 heads (according to the casting numbers) Small to mild cam judging by the tone, Shorty headers with edelbrock intake manifold and 4bbl. Headed to a job this morning and it started missing bad, Felt like popped off acouple wires. Nothing under the hood is funky, All seemes fine by looking. Kept it running and pulled every plug wire one at a time to find that the only time idle changes (gets worse) is when i pull the #3 wire. When i pull the rest, even 2 of them at a time the idle seems the same and gets no worse.. Not that i can notice anyway. As i pulled each wire i plugged a new plug into the wire and i have spark at all of them just not very strong. Rotor and cap seem new within acouple hundred miles as there not wore at all.

If i use the old wooden stick trick i can hear ticking and some other noise in the passenger side valvetrain but smooth as new on drivers side. It does have a big ugly accell super coil and im sure its a pile but its worked thus far. Pulled the valve covers, nothing seems bent or outs place/loose.

Any pointers?
Thanks Tom