94 4cyl Toyota pu has been running coldgauge not moving and heat not working well when you got home tonight you saw your exhaust manifold was glowing red what do you need to do and can you drive it?

Do not drive it. It sounds like you have a stuck valve and a stuck open thermostat. It sounds to me that a valve has been stuck open allowing combustion to overheat your manifold. Or you have an obstruction of your exhaust. Normally the valves are timed in such a manner that combustion occurs and your exhaust valve opens. In this case that a valve may be stuck open or the seat/face is damaged, your combustion is being directed right into your exhaust. Does the vehicle run like it's missing, lacking power? I would recommend doing a compression test which is very easy. Rent a compression tester from Schucks or AutoZone. Remove one spark plug and thread the appropriate fitting into the block. Remove the coil wire from you distributor. Have someone crank your engine for about 5 seconds and watch the gauge when they stop. It should hold steady or drop very very slowly and only a few psi (like 5). Write down your results and replace spark plug and move down the line. If you measure the compression on cylinder one at 160, cylinder two at 155 and so on (the numbers flop around a bit. Usually around 10-15psi of each other) then the valve is not the problem. However, if you measure one of your cylinders considerably lower or dropping considerable quick, you may have this problem. If all checks out, I would use a SeaFoam treatment to expell smoke through your exhaust to check obstruction.