UPDATE...put vacume gauge on ported nipple on carb,for vac advance on distributer...no vacume...switched carb to orig...same problem ,no vacume to dist...truck idles like new with both carbs...no vacume from carb to dist...let it warm up to be sure...is there an up and down side to the egr plate under carb? will that effect carb vacume? difference car vs truck? it has plenty of pull at the egr valve. is there a difference in base gaskets,truck vs car..there is plenty of vac for brakes, maintains 20 HG/in. per the factory gauge in dash.does not change with brake application...i don't want to throw more dollars at guess'...i even sprayed cyclo around the base of carb and intake manifold looking for leaks....nothing...this truck was just pulled out of municiple service and sent to auction...said it had fuel problems...the tank was flushed, new lines,fuel pump,2 extra inline filters,new timing chain,water pump,reman dist from ford, complete new ignition parts...then i guess they gave up...i am pulling my hair out.... should i switch to GM?....only kidding...life is to short to drive a chevy...thanks for all the help...much appreciated...

 

Here is something to try. Do you have a hand held vacuum pump with a gauge on it (the kind used for vacuum bleeding brakes and such)?
If you do, connect it to the governor fitting on the carburetor, and with the engine running have someone is press down on the accelerator while you apply different levels of vacuum to the governor fitting. If the carburetor is good, you should get some change in engine speed.

This way you can try to isolate the problem, if you get throttle resopnse this way, your problem is probably in the distributor or plumbing. I have a 1977 shop manual somewhere, and if I get a chance I will dig it out and see if there is a diagnosis chart on the governor system on the 330.

 

One thing on Ford vacuum advance systems, most are ported spark, no vacuum at idle, comes in off idle. I will look this weekend and see if I have anything with a diagram of the vacuum controlled governor system Holley and others used.