Carb/Timimg Issue

[ben.pigg.5]

Hello i have a 1979k10 4x4 which i picked up for a fairly cheap price with a 454 in it. It has a Holley 750 DP on it and is very temperamental. Most days it will run amazing then all of a sudden it wont idle runs rich spits back through the carb and just wont run.So far ive rebuild the Holley done smaller jets (due to running rich) new furl pump filter and even went as far as a regulator and also done a timing check with new plugs and still nothing my next thing s the distributor. If anybody has insite it would be greatly appriciated 

[rich weyand]

Intermittent contact on the electric choke terminals will do that.  Make sure the contacts are clean and the choke is getting 12 volts consistently whenever the ignition is ON.

If you take the air cleaner off and turn the ignition to ON (don't start it) you should be able to watch the choke gradually open after several minutes.

When it is running crappy, take the air cleaner off and see if the choke has opened up.

[Boone83K10]

Yeah sounds like the choke staying on (closed). You should have zero volts with ignition off and twelveish when on. I bet that's your problem.