Hayter Heritage 13/30 ride on mower?

New battery, new spark plug and fresh fuel. It started but felt like it was overchoking, and limited revs, I thought I would have a go cutting the grasss, it was cutting although the engine was chugging away, over choking, and going very slow, then it tried cutting through a clump of grass, mower just stopped No power at all to the engine, dead as a dodo. Please advise. 5hanks.