1997 escort sputters and idle problem

When i start my 97 escort in the morning it will stay running, but after driving it far a while, the idle gets real low. almost to the point of dying. I have a lifter that is about to go out. If i try to speed up I have to do it slowly. Give it too much gas it sputters. My friend calls my car speed buggy because it sounds like the cartoon.And about 6 monts ago i ran over a muffler that fell off a car in front of me. i drug it about 100 yards before it came loose. I think it might have done something to my pipes. recently put new thermostat in it and now check coolant light stays on.

Check the vacuum hose from the P.C.V. valve to the intake, the get holes and the rubber gets soft from heat, as well the idle air control valve(solenoid) could be sticking, if you bent or miss-shaped your exhuast this will give you a perfomance problem, inside the coolant bottle is a sensor, if the bootle is full then the sensor is screwed,