Toyota Repair: 81 toyota 4x4 vacuum problems, haynes repair manuals, emission control system

Question
I have a 1981 toyota p/u 4x4 w/ a 22r carb. engine.  It has federal emmissions, and i am in the process of repairing the entire vacuum system.  It will run with excellent vacuum when it starts. However, once I drive it for about 5 min. the vacuum disappears and the truck tries to die.  It lurches like I am in the wrong gear, and I have to keep the accelerator pedal pressed to keep it running.  After the engine cools down, it will start and run perfect.  All the vacuum lines are solid w/ no holes in them.

I thought it was in the EGR system, but I took the system out and reran the hoses with no luck. Do you have any ideas, or do you know a way to run the vacuum system to eliminate all the unnecessary emissions control systems?  Do you have a vacuum diagram for this truck?  All I can find are the diagrams in Chiltons and Haynes repair manuals.

Thank you for your help!

Trampus Wells

Answer
Check the catalityc converter, it may be disintegrating and clogging up itself and the muffler with the material, remove it and check for any loose stuff(may look like small grey pellets) that may fall out, if that is the case replace the converter and the muffler, the reason there is a vaccuum loss, measured at the intake manifold, is that the engine can't draw in any more air because of the exhaust blockage.
I do not advocate removing any emission control system components.