P0123 CODE and limp mode when full throttle

I have a 2011 c300 4matic 177k miles has its quirks and issues but a concerning one is I can’t fully press accelerator down or else my traction control and abs shuts off and car goes into limp mode and power gets reduced luckily it’s right at the top end essentially flooring it so I still rip this car around and take it to the limiter but on uphills sometimes or sometimes I need that punch and floor it and I need to do a key cycle to reset it. Is this a issue with the actually peddle switch my throttle body or potentially a wiring issue. IK IT CAN BE ANY OF THOSE. I’m asking if anyone has had this issue and what it ended up being. THROWS CODE P0123

TLDR : IF I FLOOR CAR GOES INTO LIMP MODE CODE p0123 what could it be