Cadillac Repair: 2000 Caddy Deville, throttle position sensor, coolant system

Question
QUESTION:  have a 2000 Cadillac Deville. I took it to Advance Auto Parts because my service engine light came on. The codes came out as follows:

P0121
P0420
P0506
P0507
P0420
They recommeded I replace the Throttle Position Sensor. Is this difficult to replace?
Where do I find it?
Also, I recently replaced the thermostat because the car was overheating. Now while driving, I feel heat coming from different places inside the car. around the steering column, the ashtray, floor, etc Its like there i am getting heat coming from the engine. I had the coolant system flushed today, but I still feel the heat. dont know what the problem is.


ANSWER: They should have CLEARED (erased) ALL these codes and then had you drive the car for 15 minutes at city and highway speeds to see if the CHECK ENGINE light came back ON and then retested the system for these CODES and told you whether EACH CODE was a CURRENT or HISTORY code.

---------- FOLLOW-UP ----------

QUESTION: The car is idled very high and accelerates when I do not have my foot on the gas while driving. Could the TSP be the problem? What kind of damage am I doing to car by driving it like this

Answer
Your fault could be with the TPS and or the IDLE AIR CONTROL SOLENOID.

This is why you need to have them CLEAR ALL the codes as previously stated, drive the car and re-check the codes and see which codes return and if the codes are CURRENT or HISTORY.

There is NO way to tell if your problem is the TPS or ISC until I know which codes return and if CURRENT or HISTORY.

You can cause damage to the transmission if the idle speed is in excess of 1500 rpm's.