Update, compression came back good at 160 in #3 and adjacent cylinder . Hard to reach some of these plugs on a hot engine 🔥
new coil module and we are finally getting 4800 rpm and 54mph, much better numbers. From the scan I got at 76 hours it looks like this thing never ran right from hour 1 until now. Almost no time above 4k. Feels like it's supposed to finally. Powers out of the hole and great response at any rpm. And manifolds run noticeably cooler. Happy camper👍 even the slip numbers aren't too bad, from 18 at 2800 down to 10 at 4500 and 4800.

Thanks for the update. Nice to know the solution. So many never come back and tell what the prob was.

So next question is... Lol.
I've read some places that if you pull the cats you need to get the PCM tune. Other places say it's totally fine with stock tune. So I'm not 100% confident can run it as is. I'm 99% but what do you guys think?
1) is there anyone offering a tune on these anymore? I read Whipple is not.
2) what else could I do to make this setup more bulletproof , or tune it up a bit?
If some tuning IS needed how to accomplish so I don't blow this thing up in 30 hours.
I don't think headers will yield anything without other major upgrades, which all would require PCM tuning, had anyone else played with this engine any further?

I know this is an old post but curious if you ever figured out the tuning?