Loss of power

The car has been overheating due to fan relay failure, water pump failure, crack in radiator. Car started losing power and overheating more quickly after radiator developed crack. My mechanic thought there was a blown head gasket but confirmed that was not an issue. Fixed crack, replaced relay and water pump, but still no power. Ran code and scan tool came back with P1135 (02 sensor) so cleaned both of those. No other codes.
It idles okay but not great. Put it in gear and stepped on throttle pedal. It was really slow to move and ran very rough. Kept foot on pedal and there was a bit of a surge and power increased. Had to slip into neutral and feather the pedal at each stop to keep it from shutting off. I had to repeat this procedure every time I slowed down or stopped. Drove it approximately three miles. On the outward leg. There would be a bit of a surge and car would speed up. On the return trip, the surge did not happen and did not gain power, just kind of put, putted along very slowly.