What's could be the problem with my Ford Fiesta

Hi, I have a 2002 fiesta mk6 1.4. Aztec
Recently I got in my car to go for a drive and the engine was very shuddery and I had very little power, after driving a mile or so I tried to round a corner and the car died. I drove the car home with very little power and the engine felt as though it would die any minute. Sent car to local garage and was found that there was water in the spark plug wells. He replaced the spark plugs, also tasted the water and said there was no antifreeze present. Got the car back tonight and though it is much better and not shuddery. There's very little power in the car. Even in 4th with straight strech of road and foot to the floor I'm struggling to hit 60mph. The car just feels though it has no performance at all and builds speed extremely slowly. Also worth noting after driving from garage to home there was a sort of burning rubber smell from the engine.
Any ideas, Help.

Remote wire switch for a Amplifier for my car. How to turn it on? Will this work?

Well here is the thing. I can't find the blue wire on the back of my stereo. It is a stock stereo so I have no idea. Ford Fiesta SE 2015.

I was reading about how a remote wire works and I kind of have the idea that if it receives a small amount of power it will work. So I had a (stupid) idea and wondering if this will work? Well basically I will cut a USB cord in half and expose the wire inside and connect it to the remote wire. I will also have a on/off switch for the usb. Probably won't work because I'm not an electrician. I'm stupid when it comes to these things. I posted a picture to give you an idea. I don't know how much power it needs to turn on Remote wire switch for a Amplifier for my car. How to turn it on Will this work