I am getting a loud engine rattle at lower rpms while accelrating and when I let off the gas. It sounds like something is loose but I can't figure out where it is coming from. Could it be exhuast related?
This sounds like the usual loose heat shield on/around the exhaust, and is probably the best place to start to narrow down the possibilities. You may be able to approximately locate the source while sitting in the car, transmission in neutral (since you have a manual), all the windows open, and gently rev the engine. In my experience, this noise sometimes only appears when the engine is under a load, i.e. during actual driving, which you may again be able to determine with all the windows open and careful driving on a side street or parking lot. Other than these tests, get under the car (after the exhaust has cooled!) and start tapping on the heat shields. My cheap fix has always been a large hose clamp. Note, these heat shields are there for a reason so be wary of those who suggest just taking them off. Safety first for any of these activities.