loud noises

I thought I would go to you all before I get too deep in over my head. I have a 92 SE with about 85k on it. A few months ago I noticed a noise that resembled a valve tapping noise. After some investigation I narrowed it down to an exhaust leak. The symptoms are tapping noise under load from about 1800RPM to 2400RPM, poor performance at times and terrible gas mileage!!

Any suggestions?????

Check your exhaust manifold, it could have a leak, and have your oxigen sensors checked (gas mileage), is the check engine light on?