No spark and i can only get 5V at the coil.
Battery drops to 8.4-8.9 when starting (dropping the power to +coil to match accordingly)
That's not good, but should be enough to get it to fire. Are you still not getting spark at the plugs or coil? Have you retried the +12v jumper to bypass the ballast since recharging your battery last time?
Sounds like your airgap etc is OK.
I would remove the #1 plug and make sure your engine is actually at TDC with the rotor pointed at the #1 wire. It's common to have the TDC marks not align and this could cause you tons of grief.
This only applies if you're getting spark at the plugs though. The mention of the coil not firing consistently is alarming, since it should make mucho sparks when cranking..
If it's not, then something more than voltage is amiss. If you have power to the coil and the ECU is properly grounded and connected to the coil it should run. Do you have a spare ECU to try? It sounds like you tested the one you have, but that's not guarantee it's good. I wouldn't run out to buy one right away, but if you have one to swap it might help narrow it down.
If you've got a decent auto parts store in town, they may agree to let you return a new module if it doesn't fix your issue. Some places are real hardasses, but way back when I worked behind the counter I would often do this for customers to help troubleshoot an issue.
