d19 gov or carb?

IF, pulling the choke out helps the engine to recover I'd say you have a fuel starvation problem. Even if you blow out the fuel system, you must have good fuel flow all the way into the carb. bowl. You may have trash in the carb. inside the inlet or needle valve, but it sounds like fuel flow problems.

Thanks dave, but pulling the choke doesn't help & I have a new coil and condensor (and points) but changing those didn't help from the old parts.  Always shedded and not wet.  all I know is that gov rod is slapping back and forth pretty good when this happens

How are the spark plugs/wires?

Then check out the bushing in the distributor. If the bushing is worn it may torque over and change the points setting under the application of a load. I've had some success at setting the points gap a little wider than normal to help this condition, but a rebuilt distibutor is needed to fix this.

Sounds like a weak or bad ignition coil.  When it warms up under load, it gradually produces less electrical power.  Could also be a weak battery.  Good luck.

i checked battery voltage the other day when running - 14.1 volts.  coil is new.  battery cranks it right over and it always starts right up again wth no smoke

gas cap is original - so it doesn't fit dead on tight, can;t se it being a venting problem. I can run full throttle all day and it will never quit - until it's loaded or pulling hard.  I guess the only thing i haven't checked for a while is taking the carb apart.  not really a carb man - if i take the bottom off of it and check it to see if it's clean, but like i was saying - the tank was really clean and i always use good fuel, so the carb "should" be clean.  hasn't anyone ever heard of a governor doing this?

Still sounds like fuel delivery to me but a long time ago I scratched my head over a neighbor's Plymouth car with a slant 6 for a week. It had the exact same symtoms. Would idle all day or drive down the road fine as long as you didnt try to go very fast or up a grade. About 15 seconds into climbing a grade or anytime you tried to go faster than abut 40 MPH it would start to spit sputter and if you stayed into it long enough it would die.  15 seconds later would start like nothing was wrong with it. Since every "real" repair shop in town had installed new a new fuel pump or rebuilt the carb but could not figure it out the owner brought it to me and said fix it,, or part it out. At my wits end I checked the valve lash and found problem. Lash was close to zero on all the valves, put a load on it and the exhaust would heat up and lift the valves off the seats. (For you young people the slant didnt have hydraulic lifters.) When I told the guy it was fixed and what fixed it he said, "I adjusted them down until they quit click'en, didn't know they were solid lifters." Didnt even use a feeler gauge, Good Grief!

We had a truck at work that was giving us problems, every once in a while it would just shut off going down the road or at high idle unloading feed.  Thought it was electrical gremlins and went thru the whole electronic computer brain etc along with fuel pump, injectors, everything.  Don't know how we found it, but it turned out to be a fuel conditioner cap in the fuel tank that would get sucked down over the fuel outlet. Little $2 bottle of conditioner cost us $1000 in repairs etc. 

Edited by Wil M (NEIA) - 02 Apr 2010 at 6:45am