driving under normal conditions it runs fine, but when i mash the pedal the 440 starts to pop, it misses,lacks power, it acts like it hits a wall. i checked the timing, all the componets, plugs, wires, everyting, cant get this figured out. maybe a valve train problem? floating valves? sticking? can think of anything else.
whats really fustrating is it starts fine, idles fine, it even revs up in park no problem.

My 383 was acting very similar...Would be ok under low or part throttle, but as soon as I would give it a decent amount of peddle it would pop and stutter. I messed with the carb, timing, etc...couldnt figure it out.

It ended up being my coil. I went through 3 before I found one that would last more than a couple weeks. 2 parts house ones and 1 MSD blaster...all crapped out after a few weeks. I have another MSD blaster on there now that has been good for about a year and the problem has never come back.

points and condencer would act like that also

and it can have no start with a lot of poping back thru carb

no points,no popping thru the carb, starts fine. symptons only start when rpms go up under a load

Fuel pump? Mechanical advance in distributor sticking? Secondary fuel system in carb. plugged? Could be a few things! Are you sure your timing is advancing? Check advance with a timing light. Is it an AVS Carb? Is the secondary butterfly working properly?

I have had these same symptoms before on different cars. The cause was different too.
FrankenDuster started great, idled great and would rev easily....UNTIL I put it in gear and leaned on it. THEN it would sputter, spit and stall out. That car had contaminated fuel. I drained the tank-8 gallons. Mixed in with the gas was a liquid that looked like Italian dressing. There were 2 quarts of it in there. I blew out the fuel line, let the tank dry out and put it all back together with a new filter. All better now.
The other rig was a 78 Dodge D 100 truck with a slant sick. It TOO showed exactly the same symptoms, but it turned out to have bad spark plug wires. They simply failed to deliver enough spark under a load.

Have you had the plugs out or had the wires off. Sounds an awful lot like you have number 5 & 7 plug wires switched around. At idle or very light load it will seem to run fine with a virtually unnoticeable miss being that the two cylinders are next to each other in the firing order, so wires being crossed puts the firing very close but not quite where it should be resulting in a miss under load much like you describe.

Replaced a lot of soft cams in G.M. products back in the day with the same symptom. Exhaust lobe going away? If it is it will get worse with time.

Is there a good ground from the engine to the body? My 68 dart was missing a ground, ran great until I floored it. It ran 13.01 and missed bad the whole way, fixed the ground, went 12.40's and never missed a beat.

Try narrowing the gap on the plugs. If it gets better then the coil is likely weak.

I just remembered another incident......
I am not a drag racer by any means, but I built a big motor for the Charger anyway. 440 block, 4.15 stroke crank. 10.8 to 1 compression, Edelbrock heads, 850 carb, MP '509 cam, 2" TTI headers too. 727 with a 3000 stall converter and a 4.10 SG diff. Long ago I did an electronic ignition conversion.
A local dragstrip had a car show & drag race event and I decided to race the car. I opened up the spark plug gap to .045 thinking the wider gap would make for a bigger spark. I put-putted to the venue to keep the wife from wigging out. So there I was, at the starting line. No burnout really, just a quick spin to clean the tires. The lights came down and I walked it out of the hole to avoid blowing off the tires. As I laid into the throttle, the motor started cutting out. At full throttle it was bucking, sputtering and hesitating. By the halfway mark I let up to about half throttle. I was shocked to see that I still turned a 14.83.
At home I dug in to see what was to blame. Nothing was obvious at first look. I pulled the plugs and closed the gap to .035 and went for a drive. It ran better than at the track, but was still cutting out. I pulled the distributor cap and saw that the air gap from the reluctor to the pickup coil was W I D E ! Its supposed to be set to .008 inch. Mine was at .020, 2 1/2 times the recomended gap. I reset the gap and everything was back to normal!

I've had some of these issues come up too. Too much reluctor gap, dying mechanical fuel pump, poorly tuned carb/distributor have been the main ones I've dealt with.

Mine was weak valve spring's.

Remove a variable...Maybe a friend can let you borrow a carburetor that runs on their car and doesnt have problems...Once you have that squared away, move on to another variable. Do you have a fuel gauge maybe?

Apples to Oranges. My Dart used to do that when I first got it..but it was a 1bbl carb. moving up to a 2bbl improved but the 4bbl woke it up quite a bit.

What kinda carb you got on there? maybe a power valve is blown? You are leaking excess fuel into your manifold?

Does it pop from the carb or exhaust?

I had a car do what you describe and it popped out the exhaust. I picked up a $5 spark checker and put it on a plug. I had someone start the car. At idle I could see the spark. When he pressed the accelerator the spark went away.

Mine ended up being a bad orange MP ignition box. Bought a $20 box at Autozone and it ran way better than it ever did with the old box.

TIME to find-out what your fuel pressure is.

Is your vacuum advance hooked up?? Is it hooked to manifold vacuum?