Ok. so i take it to a shop, because im noticing the car shaking a bit, rumbling, misfiring... and they did new coil pack, plugs, plug wires, and fuel injectors. and it made the car run great again. Except for one thing, it would still often misfire. He said about the mid muffler being i guess, backed up, or clogged, because from there back, the exhaust stayed cool and wasnt the right pressure or something. so he said to take it to an exhaust shop. is that about right?