You need someone that knows what to look for, I'm not saying I'm the person, but I did have my turbo/motor go out on mine and I know what that feels like. The flat four is a tricky engine to pin down when it comes to failure. I had 2 cracked ringlands with no noises, no smoke, just lumpy power delivery.
A turbo will run you about 600-however much you wanna spend on it if you do the work yourself. A motor will cost 3k and up depending on how much work you can do.