i bought this car several months ago and it had a bad carb...i got a good carb from a car that was running before it was wrecked...after reading a lot of other forums, i decided to devac the car....i have not been able to get it to run since...i'm certain there are no vac leaks....

the car will run really well until you get it on the open road and floor it...at top end, it stumbles, stalls and backfires...i bought a weber carb adapter and have tried 4 good weber 323/36's on it and have messed with jetting and it does the same thing...it runs well to about 2500 RPM's then it stalls and starts backfiring...i know my webers are good because i took them off several well running BMW 2002's that I own...i bought 2 more honda carbs and each does the same thing

any help will be greatly appreciated