Missfire backfire tach jumping

Ok got an interesting one for a month now Ben driving my 85  80 miles a day to work and back still got the timing bug where it's stuck at base time but it's been running ok till now.   Driving down the road it will cut out like you shut it off then come right back to life sometimes it just misfires and sometimes it backfires out the exhaust without missing a lick every time one of these happens the tach jumps all over the place it's Ben happening a little here or there tonight it actually got worse every time I'd try to Cruse along anywhere under 2000 rpm it was hirckin and jerking dieng popin and banging.   A few times whengoing slow or around corner it has died on me where I had to stop and start it again because I was to slow to pop the clutch when you hit the key it acts like the timing is advanced to Kingdom come won't turn over at all till you let it sit a few then starts fine.       And also when it dies now the tach will sit there and jump around even with the engine not turning dead stop on side of road.  Just key on

I have pulled plugs and wires off all are new I've done a spray test on the wires with salt water to try even harder to get em to show an arc no problems found I put a new coil on a month ago old one was arcing to ground I opened up the distributor I don't see any signs of arcing and it doesn't seem to matter if it's raining or not all parts inside feel ok nothing loose.      Just curious of some thoughts I have a theory of a bad coil or ignition module but thoughts welcome.        

You probably have an ignition module that is in the process of failing completely. I used to deal with that on MGs with the Lucas Opus ignition systems. That was basically the way I could get them warranteed. Same with the infamous Chrysler "lean burn" systems. In both cases, if it wouldn't run and was over a year old, the owner was SOL, if it ran like crap, missing backfiring or whatever, it became an "emission" warranty item and was cover to 5 years 50,000 miles.