First post on MBWorld, i've probably broke the internet before posting this so please if I may have possibly missed a full walk-thru on finding out exactly what my problem is please forgive and guide me in the correct direction.

First things first.

Over the past couple months my girlfriend has been experiencing odd acceleration issues when on freeway trying to gun it on the on ramp sometimes it'll accelerate quickly as normal, other times it feels like it just cuts power and no acceleration happens at all then goes back to normal.

I took vehicle for a drive one day & noticed what she had explained to me about gunning it and when I put vehicle in park I noticed the idle creep up to about 2200 rpms and hang there, thought it was out of the ordinary so I turned vehicle off and back on and vehicle idled fine. Few days later nothing else had happened vehicle had idled and accelerated normally .

And just when I thought maybe this sinister issue had finally sorted its deal with the devil out it came back to bite me in the *** one morning, no throttle response at all, check engine light came on, and car in limp mode.

P0120 - Throttle/pedal position sensor/Switch A Circuit

Ran the codes with a scan tool from autozone it produced the code above, I searched high and low on the code and checked all pins connector and said what the hell spent the $100 some odd dollars on new throttle pedal sensor, tried to relearn it back to the car myself as others have with prevail.

Off to the stealership it goes knowing they are going to tell me exactly what I don't want to hear. $145 later for programming of new sensor, car still does not have any throttle response and the tech told the service adviser it's going too be the throttle body actuator. Now you know they wanted $1800 too get the parts and labor to fix this issue however, that not going to come out of my pocket.

HAS ANYONE.. experienced and issue like this and what was your story and how did you come up with a solution?

I will get another throttle body and install it myself, I should be able to cycle the key a few times and do some smooth pedal activation's too restore/relearn the pedal value.

HELP. I'd really appreciate any input I can get.

 

I had the same problem. I replaced the throttle actuation sensor with no success. After a couple of months I figured I would follow the wiring from the actuator to the main computer. I disconnected it, waited one minute, and replaced it. The truck has been running perfectly ever since.

 

just posting in case it helps anyone, had this issue (similar to the above) on the ML320 2001, noticed that even if I full throttle the RPMs don't seem to be going up, even if I pressed down on the downshift button under the accelerator pedal.
A few lights where on (BAS/ESP light I believe and CEL), didn't use the car in that morning.

Late in the afternoon, I tried again and the car worked as normal. Pulled the stored fault codes and got P0120.

I pulled the connector going to the actuator sensor in the engine bay, sprayed some contact cleaner on both sides of the connector, let it run off and reconnected.
I also cleared the fault code.

Issue seems to have disappeared and car is running as normal. Good luck!