Setting up a holley stock 350

I will try to keep it short
Been having this dilemma for bout 6 months
My old motor lost compression in cyl 6
So new gm crate 350 base 290/350 all stock
Topped with eldelbrock intake w egr (for smog)
Qjet from national carburetors
Ran perfect brakestand with 20's(sorry) no problem drove like a new fi car loved it exhaust made burble tones I never heard before. It was heaven
Then I thought ill retune the carb one last time just the idle screws
So in till it bottoms lightly out 1 1/2
Ran like shit after under 10" hg under 1000 rpm
Fought with that shit
Sent it back under lifetime warranty
3 times over 2 months
They say its test ok with us back to me
So when I sent it back the 3rd time (later ending with refund)
Sent the origin qjet (failed rebuild attempt by myself)
And ran great ...in idle fell on face past part throttle
Another rebuild shop ran almost great slight stumble hesitation tried more and less tension on air flap spring couldn't get it
Plus I couldn't spin my tires just loads up :'(
So fuck it all reman holley 4160 (Holley 0-80451)
I tuned it getting 19" in park wasn't able to tune in gear (no one to help/I used to put the rear on jack and let it spin free good idea or no)
I can spin tires good do a rolling 10 ft one too but when driving if I lightly press throttle pulls smooth up until it starts to get higher rpm 2500-3000(no tach)
Then I has a flat spot then picks up again
If I keep part throttle its accelerates normal for a couple seconds then Dips back down again
If I stuff it. Hesitates and may backfire /want to stall
If I stuff it and downshift manually it goes hiccups then pulls hard
Any ideas I puts it on on Sunday just trying to fine tune it
I tried all 3 positions on the red cam no big difference
The disscharge nozzle is 31
Accelerator pump lever is set proper
I still have to check float adjustment
Only things I think of are changing the disscharge nozzle size. Or
I have improper transition slot clearance
Any suggestions are welcome and please educate me its my first holley
Thanx

I think you're on the right track with checking the float level first.

When you set the idle, how far out did you have to back the idle screws out to get good idle? (I ran into a problem where my 4160 was waaay too lean, and i had the idle screws backed almost all the way out to get good idle. You shouldn't have to back them out more than full turn or so, depending on the motor.)

I'd also check for vacuum leaks and make sure the secondaries are opening properly.

The idle corcut is reversed so out is lean and in is rich
I started at 1.5 turns but had to keep going in to get a smooth turns I am almost at the max maybe 1/2 turn away
I seen this issue on a review for this carb on summit
Gonna set floats tonight then test see the difference and then ima tune it again

Found my issue was a overlooked error on me apparently there is a vacuum leak at the intake manifold in the middle bolts
Idk why I tightened I. Pattern to spec
Used edelbrock gasket with gaskanich guess im going heavy with rtv on the intake flange to gasket side now. Dame hate when im stubborn and just go no its fine I just did it.
Enough talking here u go
https://youtu.be/Lt0tUjUh60Y
https://youtu.be/tAtHvlGuxGw
Verified vac with brake clean I could stall it if I sprayed heavy to make a puddle
Tightened intake a little helps some but still present

so I asked a guy at my new work what he does to mate aluminum intake to iron heads
he recommended to clean all surfaces baby ass clean and coat both sides with rtv rubbing all over did this and torqued everything then let it dry day and a half before putting fluids and another half day before starting

screws in and out 1 full turn
started right up had to bump up idle screw to idle alone after off the fast idle
set my timing w/ hose plugged and set at 10*btdc (cant bump more due to smog)
like being under 1 full turn out pulling 17hg before was pulling 20hg with the q jet
still have that hesitation on the line it goes back and forth of accelerating and falling on its face in the transition phase
if I go light pedal it goes normal but as the rpm goes higher it feels like its sputters
my ignition system is good  MSD distributor/cap/plugs/wires under 3k
if I keep in low it pulls better on the higher rpm but I kinda got to drive like an asshole to get around
I went to a spot to test I can break the tires loose with 245/40r20s
and leave two black strips

if I stuff in reverse it just goes tires break loose and it starts pulling away
put in d and stuff it , it goes 1 sec power falls off and comes back on
I can brake stand and take off too just not off a standstill very annoying

I was thinking the gasket didn't seal right I was thinking maybe I used wrong gasket but the edelbrock intake 3701 recommends using 2701 gasket. Although it says for edelbrock intakes with edelbrock heads but also say ok with stock heads performer intakes . Your thoughts??
I sprayed carb spray by the valley flange and the idle changed a bit I blocked off with carb board
and sprayed again and it was still present so I hope its just cause I reused the square bore heat insulator
I'm gonna stack 3 1/16" gaskets that were included to replace the insulator and see what happens.

Bring up the off line issue can a worn transmission cause these symptoms?
I wanna get this sorted to pass smog and start working on the body work and t56 trans...  I said too much
I will try to post pics asap broke my phone new one tomorrow

Carb clean revealed a vac leak at the base so I used a stack of 3 square bore gaskets as stated in holley manual and then checked that 3701 intake is ok to use without adaptor .edelbrock responded to summit stating no adaptor required ,well maybe true with edelbrock carbs but not holley
Went to O'Reilly s picked up a square bore gasket and a went gasket cometic very nice stuff rigid yet soft enough to seal
Sandwiched the adaptor plate between and bolted it up
Got creative with a old interchangeable screwdriver with bit removed and a hammer to trim corners to let bolts thru due to bolt patterns being different
Sealed up nicely sprayed carb clean all over stayed steady
Set the screws till no hesitation snapping the throttle but still tuning in park
I can spin tires in reverse off line but not drive it goes just not as aggressive as id like.
I can do a burn out well enough no bogging like before
I can drive relatively normal dont have to shift manually but still lacks power it putters a little when above 2k rpm I would say
Maybe fouled plugs I rechecked timing a 10 btdc. Newer cap and ign stuff less than 3 k