I agree except for one thing. Tight valve lash on one car does not mean that every vehicle suffers the same valve lash problem and my opinion is based on the compression test and valve lash adj. that was performed according to the OP.
The OP states they do not know if the compression was tested before or after the lash check. (should be both)
Knowing the minutae behind this problem could help in knowing for sure.
One overly tight valve can cause stalling though as it throws the manifold vacuum off which in turn affects the entire engine management system.
It could also be that this entire thing is a botched diagnosis and the lash problem is one that may or may not have existed or meant that much. A valve being held open by .001 of an inch is a serious problem. A valve that has .001 lash clearance when hot is dangerously out of spec but should not cause this stalling problem. As per the usual, the devil is in the details.