Lost power
 

So here is what I got. Have a '95 Camry V-6. The water pump was leaking prefusely so we (actually the wife didnt give me the details who...ended up being a kid who lacked skills) took it to a mechanic and had it replaced. Apparently after he replaced it he didnt tighten the timing belt down all the way. So he had some serious engine noise and then realized he broke it. So, he "replaced it" and now it works. Problem is...it sounds like my headers have a hole in them or something and it feels like I'm driving a scooter. All the power is gone. Any ideas what I (very inexperienced mechanic) need to look at as the issue? I do know the clutch is fine. I'm just trying to figure out what is screwed up. I guess the plan is to go and take apart everything like I was doing the pump myself and see if I run into the issue.

Never let your wife take your car to a family friend who works on cars without meeting him. He'll turn out to be a 17 year old kid. FML.

The noise is from the exhaust system?

Look at the exhaust system under the car located about where the firewall is for something looking like a wire mesh pipe connecting sections of solid pipe. The mesh pipe can leak, check for leaks.

How does the engine idle?

Did the "mechanic" work on anything else beside the pump? Was the timing reset on the engine?