Car accelerating on its own to 35 mph?

2008 chevy impala 3.5 flex. check engine light turned on for a misfire on cylinder 5 so I did a tune up, cleared the code, and the light turned back on. replaced the fuel injector, cleared the code, and it turned back on. Ran the code again and a new one showed up (p1174 fuel trim cylinder balance bank 1) along... show more 2008 chevy impala 3.5 flex. check engine light turned on for a misfire on cylinder 5 so I did a tune up, cleared the code, and the light turned back on. replaced the fuel injector, cleared the code, and it turned back on. Ran the code again and a new one showed up (p1174 fuel trim cylinder balance bank 1) along with the cylinder 5 misfire. Took out spark plug and switched it with cylinder 4 and regapped the plug for cylinder 5 (even though the plugs are supposed to be pre-gapped. Thought it fixed the problem.Couldn t feel it misfiring. Car was still idling rough and I thought it could be the engine mounds.(I know they need to be replaced). While I drove the dash lit up and said engine power reduced. Ran codes again and the same codes popped up plus another new one(app sensor 1 circuit low volt).replaced the gas pedal and the check engine light turned off by itself. Didn t have to clear it. Cleaned the throttle body and the maf( used designated cleaner for each). Drove it and noticed the car accelerated by itself. I drove it until the light turned on, ran codes and all but one cleared( p1174).was told it could be the TPS I replaced it and it still continued.was also told if you disconnect the MAF sensor and the car keeps running it s bad.tried it and the car kept running so I replaced that also. It continued.Thought maybe it s a faulty acc pedal so I swapped it for another new one and it s still doing it. It didn t start accelerating by itself until I replaced the acc pedal
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