Next I would try the MAP sensor....but...

Does it run smooth or does it sometimes run rough...?

When it cuts out can you describe it more....? Is it consistant...? Does it sometimes cut out but then doesn't all the way die....Like a shutter....

I have a 89 Astro that does this and it is caused by the torque convertor....I does it mostly when cold and is intermttent....The convertor tries to "lock-up" at idle and when it does it cuts out...