MG Car Repair: 79 Midget, zenith stromberg, vacuum gauge

Question
QUESTION: Hey! First off, thanks for answering my question. Lemme know if there is anything I can do for you. Here is my problem: The car runs strong for about 1-2 minutes. then it 'dies' by dies I mean it can only run at low rpms. I know my electrical and cooling system are great and so I am looking at my carburetor. I think that the float chamber (is that a part?) is not getting gas quick enough.

Is that an adjustment? what do you think. PS any links would be great :) thanks. It is a us model with the zenith stromberg carb.

ANSWER: Martin, if the car slowly loose speed and pushing down on the throttle seems to have no effect. Put a vacuum gauge on the intake manifold and read manifold vacuum at the time it slows down and let me know what the readings are. Are there any backfires or missing noted or is it a smooth transition to slow running? Also if you shut it off and start right back up will it run ok for a short distance?
Howard

---------- FOLLOW-UP ----------

QUESTION: Will do :)
Okay, the only thing is that is is not a 'smooth transition to slow running' also there are no backfires either or missing. I drive for like 3 minutes and the car dies almost as instantaneously as if I turned off the key. (however the engine is still spinning because it is in gear and I am going fast.) This is when I note that the tachometer still functions.
As long as I keep the pedal floored, there is no power.
Yet, if I let the gas off considerably I cant get a little power back in 'spurts'. Then If I stop the car and wait a while, it will run great again until the same thing happens.  I put in a thermostat that opens at 160 and so this all starts happening before it gets hot.
Also, it only happens when there is a load on the engine (ei if it is cutting out etc. and I stop the car, open the hood and rev it exceedingly, it will rev fine.) (that makes getting a vacuum pressure reading hard but I'll try.)
Thats Howard.
Marty  

Answer
Run the vacuum hose out from under the hood and put it under a wiper blade so you can see it when driving and having the problem. It useless info after you stop and raise the hood.
It is also possible that you have a fuel starvation problem so you may need to run a test on fuel pressure too. Most vacuum gauges have a small area on the gauge for fuel pressure so look at your gauge and tell me if you can read fuel pressure with your gauge. That will be the next test, but run the vacuum test first.
Howard