Since I've owned the vehicle it has been low on power. I have verified this by riding/driving other members cars, as well as a previous insight I owned.Did something happen that leads you to believe that the ECM is faulty?
By "car cycling into purge every 30 seconds" and "not reliably going into lean burn", do you mean that you're entering lean burn, but it goes into purge every 30 seconds (which doesn't sound abnormal)?
Is the check engine light on? If so, what codes are being thrown? (may be time to peel the onion)