There are too many possibilities to speculate. If we did suggest things it could lead you to repeatedly spend time and money on the wrong things hoping to get lucky with a cure.
I would repeat the good advice given by olduser 1 on similar posts. Try to find somewhere reliable that will do a diagnostics. It may cost a few bucks but should identify fault codes that could save money on uneccessary work.
The strange noise may automatically be cured when the poor running issue is fixed . Or it may something additional and unrelated . For instance it could be something mechanical on the engine, air con compressor, alternator, gearbox, clutch , loose rattling pipe work etc ,etc that wouldnt necessarily show up as a fault code on diagnostics. But an experienced mechanic actually listening to the car may recognise it and identify it immediately.
