1998 Altima

My altima just recently started to act up it shrugs and feels sluggish and the gas is coming out the muffler it burns to much fuel and u could smell it when I drive the car shakes it seems that the mixture is too rich and it gave a code p0300 I wonder if that code has to do with the problem I wonder what the problem could be also my drain fo the air conditioner was clogged so I had a leak inside the car and maybe some wires got wet I wonder if that could be the problem