I hava a samurai with a 1.6L 16 valve swapped into it, it has run fine for the 4 or so years I have owned it while doing regular maint.

Anyways, I have an issue where it runs perfectly fine on cold startup up to the point where it enters closed loop operation, at that point the idle slowly starts to drop down, then begins to misfire and finally will stall.

I have compression tested the motor (good), changed the oxygen sensor (was suspect because it would only stay at .8v) and changed the coolant temp and mass air flow with know good working ones without any change to my problem.

If anyone knows what might be the problem, can recommend a knowledgeable mechanic or shop to have look at it, it would be much appreciated. I am located in Vancouver BC Canada

Thanks for all the ideas, but all the simple things had already been tried. ECM is/was the problem

What year was the computer?  You usually only seem ECM problems on older models, 93ish.  My brother had a similar problem that was actually caused by the EGR valve sticking.