insame1, thanks for reminding to check the IC Pump, which the shop did tested it by connected up to a car battery, it did spun on the floor, before its installation. And when I turned off the ignition ( after my last long drive ), there's still an electrical current buzzing sound coming out of the dash area for a few seconds before it goes off ( indicating the IC Pump working? ); told by most owners as well.

One thing I forgot to mention is that I saw the temperature bar dropped a notch even after driven it for a long while, though it was still above 80. However I better stop driving it and take it into the shop ASAP, as insame1 said I could be overheating my SC and IC.

I'll check the IC Pump's wire connection along with the IAT sensor. Thanks.

"Ill tell you one thing though you don't have a "Cadillac converter"
One more of this for me...

Your car temp may not increase at all if the IC pump fails or if there is no flow. You need to hook up a reader (I use torque) and read the IAT temp.

Got it and thank you again!

Would you happen to know if there's a reliable / price reasonable independent repair shop here in SoCal in / by S. Pasadena that knows our cars. Am in the middle of preparing a business trip for oversea and hoping I can get her cured before I fly off with a happy mood. I'll also do a search for such repair shop here now. Thanks.

Haha! Voice dictation without thorough proofreading always gets me in trouble; "Cadillac converter"

Did two diagnostics today, both are aiming at the Throttle Actuator, $1260 for the parts and $200 for labor. Scheduled to do it tomorrow around noon. Painful!

Though no power was lost at all today ( around 60 miles round-trip; all driving conditions: stop and go, freeways... ); drove it easy without flooring the gas pedal, may be the valve inside of the Throttle Actuator gets stuck when the gas pedal is floored? As matter of fact, power was lost right after the gas pedal was floored previously, come to think of it. I wish the moving part inside of it that gets stuck can be repair / lube if that's the case when not involving electronically failure, instead of paying for a brand-new one!

It wouldn't let me upload all 4 pages at the same time for some reason!

Third page.

Last.

Got my adrenaline back! though gave a kidney; replaced the throttle actuator, parts and labor $1540! So far so good, hope that's the cure.

Gunk built up where open / close flap at rest, thus it gets stuck! Is it possible for the dirts to get into this air tight area when all the housing screws are tightened properly?

Can anyone please tell me if it'll work again when the gunk is cleaned off provided if the electronic part hasn't been damaged or areas that are impossible to clean? Though I cannot return my new one but it will be good information for ones who encounter this same situation. Thanks.

Different angle.

The problem with code P0120 is that it can be either the TB or the pedal. it's a shared code. The dirt you see is not good but it is nothing serious. if the problem with the TB, it is most likely the electronics inside under the black cover. Specifically the potentiometer. Sometime just clearing this code can go a long way and by you some time. Let's hope this is it and your problem is solved.

Yes, that's what they'd told me also; could've been the paddle sensors as well.

Dirt built up like this in the TB at only thirty-seven thousand miles that caused problem already, am I going to run into this issue again after another 37K miles or so down the road? Any preventions other than the shop told me to add fuel injection additive / gas treatment every 1K to 1.5k miles ( always have been using good brands of premium gas since got it out of the dealer new; mainly Mobile )? And my own thought of to make sure that there's no one to tampered with the screws tightness on the TB housing?

Thanks for your positive thought!

what kind of filters are you running?

Just have found this link after you've brought it to my attention and am looking into it ( I don't remember if my past scheduled maintenance had replaced it ):

https://mbworld.org/forums/c32-amg-c55-amg-w203/416371-diy-change-fuel-filter-c32.html

Thanks for your helpful tip.