Car sputters at 60 mph, Manual trans, RPM and gear make no difference. Hissing from exhaust. Removed exhaust, problem persists. Help?!!?

Are you sure the origin of the hissing noise was the exhaust system? I ask because if the hissing noise was from some sort of vacuum leak rather than an exhaust leak and removing the exhaust just made it so loud that you could no longer even hear the hissing, a vacuum leak could explain the run problems and fairly significant vacuum leaks can make a "hissing" noise like you are describing..

If something like the intake manifold gasket or some other part of the intake tract past the mass-airflow-sensor is pulling in air when it's not supposed to, you'd have unmetered air entering the engine and that can cause sputtering and all sorts of other poor run conditions.

There is a way to check for vacuum leaks at home using an UNLIT propane torch. However, since there is some potential danger involved in using raw propane gas to find a vacuum leak, I'm not going to explain how to do it. You can look up exactly how to do it online and at your own risk if you're interested in trying it instead of taking it to a shop. If you decide against using a propane torch to track down a vacuum leak of unknown origin, I'd recommend letting a shop equipped with a smoke machine (ask to see if your shop of choice has a smoke machine, because it's important they do in this case) try and track down a vacuum leak. Good luck.

If it was my 65 Ford Falcon I would suggest replacing the fuel filter. But there have been thousands of motor variations since then - so no clue.

Don't know what kind of car it is. Don't know what engine it has. Don't know the miles. Can't help!