Hesitant Pick and Check Engine Light

Hello. I need help. My 2003 Alero is hesitant to pick up. When I go up a hill it won't go over 30mphs and there is this hissing noise coming from the engine. We can smell smoke in the car when I start it. My gas is decreasing much more than usual. I had a mechanic friend recommend to change the gasskit (spelling). My check engine light is on also. My check engine light was on before this and a local repair shop said that it was the Sensor 2 and not that important.

Please help with advice and around the price I should pay for the service. People cheat you, male or female.

Thank you.

Welcome to AF.

It would help to post which engine you have. 2.2L Ecotec or 3400 V6?

Also post the diagnostic trouble code(s) (DTC)?

It could be a clogged CAT converter.