1967 Ford F-250 loading up

The carb may have a float level set to high and maybe some timing issues. As well as other things. What kind of carb is on it and check vacuum lines for leakage especially to trans as the one going to modulator would get oil on it and go soft and suck together. But iti si probably more carb related so let us know what kind it is and model if you can find that.

It does that because it 's not getting enough fuel then it does. See the pics I've sent the numbers on carb settings are for dry float and wet float. Check to see that float will actually float and not sink as that may be your problem with loading up put it in a jar of gas for about 10 minutes if it sinks then replace it. Check inside distributor where vacuum advance arm hooks up to dist breaker plate if either are worn replace worn part also check breaker plate for moving sideways an dnot moving correctly off of rotation point they wear there as well. Also if single point setdwell with dwell meter at 30 degrees fords ran best there and make sure to put a little bit of lube on cam for points as they will wear quickly without and screw up timing. Timing shold be set at 6-10 degrees whichever you like and gives least amount of spark knock higher timing will give better power. Also check firing order after you did all of this then let me know if you still have the problem.