As many know here I have been fighting an idle issue with my DZ. It starts easily and after the choke is pulled off I can get a good idle in the garage. Then I drive it for a while and get it good and warm it won't idle. It slowly dies off over about 5 seconds. Looking at a vacuum gage connected it looks like the vacuum signal disappears. What could cause this? Is it valve adjustment? A auto repair shop mentioned reversion pulse. It is not timing or the carburetor. Could running the car on a scope find anything? The car runs great otherwise.