Lack of power slight hesitation throaty sound from engine

Partially blocked cat / exhaust ?

A little more info car runs ok until it warms up then noise becomes louder and lack of power starts struggling to get up hills in 2nd gear thanks for your answer does this add any weight to your answer thanks fb 240

please can you help me, I have a 2004 astra coupe convertible, at times its like there is no power when accelerating and then most the time if I turn it off and restart it the revs are there and it will drive fine again? Ive just brought a fault finder and its not showing any codes up!! Ive not long brought this car and I'm worried that this will happen when my kids are in the car as it gives no warning that its gonna do it, sometimes the engine management light comes on, but hasn't since I brought the fault finder and put it on the car!!! please can you help

Thanks re my problem was the cat, thanks very much / next problem flat battery been told down to radio can it be repaired or any other solution to this thanks