Dies as if it has a total vacuum leak

1986 Toyota 22r engine, dies as if it has a total vacuum leak on take off, after running at 55 80 it is ok, runs like a champ, just wont take off.

Stalled started off with a slight backfiring, which eventually became a large "45 caliber" sound. I first thought that I was getting a rich mixture in the exhaust, when I let my foot of the gas it would go off, ka-BOOM! I took my exhaust system off, carefully examined the entire system and found two small leaks, which I thought might have been providing the fresh oxygen that would cause the ignition in the muffler. No difference.

I then took all of the top vacuum lines off, one at a time and eventually found one with a small split. Replaced. No difference. If I take off, as if I had an egg under my foot on the accelerator, I can get it to take off, but if I press any at all it will die. Oh yes, the backfiring stopped, after I took the hose that goes to the E.G.R. Pump that goes to the carburetor of the breather and put a bolt in it to plug it up. But it will not stop nose diving.

I almost got ran over with a semi-truck that assumed I was going to continue, not come to a complete stop in front of him. A rebuilt carb for this truck is $576. I paid $1150 for the whole truck. Can' find a rebuilt any where. Or a used one either.