Most likely the intake manifold will need replaced, it can be expensive.
There is one issue for this fault. The manifold runner control actuator needs replaced and this will solve the problem.
High idle can be from a malfunctioning coolant temperature sensor, idle air control, throttle linkage problem or a intake manifold leak or (vacuum leak). I have come across many v8 fords with intake manifold leaks. Unplug the connector on the idle air control, if it still has a high idle, it will either be the idle air control seized, throttle linkage or a intake manifold leak (air leaking into the manifold through a gasket or vacuum leak) If the idle comes down it will be the coolant temperature sensor or a power train control module problem. A scan should pickup a coolant temperature sensor out of range fault code if it's at fault.
Check your o2 sensor on the exhaust manifold. If that's not it, try the heat control sensor on the intake manifold. You might also want to test out a new ECM and the timing.
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The OBD code P2001 indicates a problem with the intake manifold runner control system, specifically related to the function of the intake manifold runner control valve. To fix this code, first check for any vacuum leaks, ensuring all hoses and connections are intact. Inspect the intake manifold runner control valve and its actuator for proper operation, cleaning or replacing them as necessary. Lastly, clear the code and perform a test drive to confirm that the issue has been resolved.
It could be running lean. Check the fuel filter. It could also be a vacuum leak or the EGR valve. It would probably be a good idea to not run it much until you've worked out the problem. There are quite a few possibilities, and some of them are not very expensive, but if the exhaust manifold is getting that hot you could be damaging your exhaust valves. If the exhaust manifold is glowing, it's not the cat-converter.
Could be a problem with the thermostat housing or it's gasket, could be a problem with intake manifold gaskets, could be a problem with heater hoses or the fittings that screw into the manifold.
If this is a '99 through '02 Cougar, this sounds like the so called "Moosing" problem, which is a problem with the Idle Air Control Valve (IACV), and is fixed by taking the IACV out, its connected to the upper intake manifold, and either cleaning it thoroughly, or replacing it.
This is a problem best left to a qualified gunsmith.
is it to expensive
The EGR valve is located on the top of the intake manifold rearward of the throttle crank under the cowl. If you suspect a problem with the system, you may want to check the EGR control solenoid, the EGR control backpressure transducer and all vacuum hoses.
You have 2 zone temperature control control. The heater control valve has failed and is open allowing the passenger side heater core to stay hot. It is a very common problem and expensive to repair. It tends to be an intermittent problem and sometimes will work properly.