please help

i just bought a 92 plymouth laser rs tubo off my uncle. He sold it to me for cheap because he just bought a new car. Anyways the car is loosing power dramatically and it's almost like the turbo isn't kicking in at all!! The turbo was replaced last year with a used working one. Also the car is burning oil and a bit of black smoke is coming from the exausht. I just need some advice before i bring it in to a mechanic.

Could have oil on the pistons. Maybe bad head gasket and loosing compression

Maybe it could be the rings not to sure. I'm not decided if i want to bring it in to a shop or just start ripping the engine apart.