The ECU does not reset if disconnected.
I regularly disconnect my battery when leaving the car for more than a week or two.
For a high rev lack of power I'd check fuel flow and HT pack/leads.
A very rough way, if you quickly rev the engine without load and it runs over 4,000 for a short while then drops back suspect fuel, if it cuts at 4k revs then I'd check the HT system.
