so I have installed new plugs ,wires , points ,condenser , coil ,fuel pump , rebuilt carb , replaced cracked exhaust manifold . shes firing on all cylinders . Has right at 118 pounds pressure on all cylinders . I have moved timing all ways possible .set at factory spec now . she starts right up and idles fine. But at im guessing 1000 rpm plus misses bad .if you continue to give her fuel she will start to backfire and stumble bad. I thought she might be starving for fuel so I tried dumping some in to see if she would clear out, but that didn't help. no intake leaks either . Im out of ideas . I bought the truck long distance and the guy said it ran great . ive dumped another 800. 00 or so plus my time and still runs bad . If broken valve spring or something would compression still be good ? Any ideas will be appreciated