AFAIk there are 2 Ecutek tuners in WA, MMS and Race Torque.
When I first got mine, it would stall at idle, and run lean at higher revs, so different, but a tune did fix it, when vacuum leak was't found.
Could be sucking in un-metered air, but what would I really know about your car?
Find a mechanic you like, as its a constant fault rather than intermittent, should be easier to fix, but its not like going to a doctor with a broken bone and its sticking out of your arm. They'll start with the usual obvious things that may have caused this and go from there.
It may take more than one visit to fix. It may also be more than one issue.