Sputtering

On the passenger side of the block there is a Y in the transfer line going from the front of the engine to the heater. Take the line off the Y that runs from there around the back of the head (I think it has a clip that bolts on to one of the bellhousing bolts) and unhook it from the back of the intake. You can use a short piece of hose with a bolt in it and clamp it securely or you could put a straight piece of tubing in to do away with the Y.

The water returns to the thermostat housing (near the bottom I think) with a very short piece of formed hose. Unhook it and you can use a pipe plug to plug it at the housing, be careful trying to get the hose nipple out, if it won't come out you could use the hose with a bolt in it there. You can plug the ends of the intake with pipe plugs after you get the hose nipples out. You might want to blow out any water out of the intake before you pug it off. If it lays in there long enough it could corrode. I would drain out as much of the block and radaitor before you start doing this as it may be a little messy. Take the bottom radiator hose off the pump to get as much out as you can. Refill the radiator and check for leaks.

If this doesn't help the next place you could look is whether your fan clutch is working properly.