Nissan Repair: Weird symptoms, cat converter, exhaust manifold

Question
Just got my 99 sentra 1.6 liter back from the shop.  They replaced the radiator and both belts after the radiator cracked and the car over heated.  As soon as I took of from the shop I noticed that the idle was way too low and it very little power.  The car will not exceed 50mph under any throttle setting.  When looking the engine over, I noticed that the exhaust manifold was glowing red where it started it's 90 degree bend back towards the muffler.  Any thoughts?

Answer
Hi Luke -

your exhaust system is plugged. check the muffler and the cat converter for blockage. The way to do that is take each one off, one at a time, and notice the engine performance. Once the performance improves, you have found the problem. The shop should have caught that -

Hope this helps -
aloha
calvin