...Vac. gauge reads 11-14 off the back of the manifold. holds pretty strong at 14 but occasionally dips to 11 and then back up to 14.
That's too low. I'm going to go out on a limb here and say your ignition timing is too retarded. Among perhaps other things, but this is a critical point to check before chasing other tails.
The steady is a good thing, as mentioned, but a stock cammed 289/301 should pull a minimum of 18, and more like 20 at idle. Mine runs 21 when I have my timing set to my preferred 12° BTDC. Don't remember what it was when timing was at the stock settings.
Before you do anything else, find the #1 spark plug wire at the distributor, and then checking each one counter-clockwise from there, find out what firing order you're sporting. Looks like the more modern 13726548 from here. Yours "should" have the older 15426378 of a 289 unless the cam was changed out. Sorry if you already mentioned that, but I didn't go back over every post.
If it's off, it "should" also be running rough as well as weak and with a weak vacuum. But it might be so well balanced that it's still smooth and just weak.
I'm thinking it would be odd to have the wrong firing order and a steady vacuum signal, but I've seen stranger things.
Once its warmed up I am able to fully open the choke!! Finally!
F/M screws are 2 turns out.
Hey, a result!
But more to do still...
However, I give it some gas and when I let up on the pedal, it starts popping pretty bad. Is this a lean or a rich symptom?
Popping out of the exhaust, usually too lean. Popping out the carb, incorrect timing.
Again, "usually" but as you'll find out there are few things etched in stone.
Also, doesn't seem to have a lot of power when I test drive it down the road.
It wouldn't at this point. Too low of a vacuum signal, and too lean (theoretically) and unknown timing I think?
that also leads me to a rich mixture.
Possibly.
Should i go "IN" on the F/M screws? I have played with it and it doesn't really impact the idle or vac reading.
Neither. Not only do they have ZERO effect on how your engine runs under load, but if they're not making any difference at idle, then they're not making any difference.
This is likely because your carburetor is still running with the idle speed screw turned up to keep it running. Doing so also eliminates the idle/air mixture screws from the equation.
One guy told me it may be a compression issue with one of the cylinders?
Certainly could be. But too many other things as well, so still need to check. You can do a load test in each cylinder when you get it running normally, or you can rent a compression tester and know for sure. But I wouldn't at this point only because there are too many other questions still in need of an answer.
Or too much pressure from the fuel pump.
Too much pressure could make it run rich. But we don't know it's rich yet. Yes, that plug made it look that way, but if you have a super lean mixture causing what's known as "lean-misfire" then you are still going to have unburned fuel in the cylinders making soot.
Again, hard to say at this point...
The idle mixture screws make no real difference when I move them in and out. I will check the power valve.
They can't. If you still have the speed screw turned in so far, they're inefective at best.
I finally got it to idle low (normal) last night. but choke had to be pulled half way out.
Too lean. Too retarded.
Also, when I step on the gas, it stutters a little and then finally picks up.
Also too lean.