Engine power reduce

Question

P0641 I've change pedal, tps, battery what else could it be ?

Answer 1

P0641 this is the 5 volts reference voltage of circuit 1,this goes to the APP sensor 2.  This 5 volts reference voltage is shared with the MAP sensor, the Fuel tank pressure sensor, The A/C pressure sensor, The Engine oil pressure sensor, The Camshaft position sensor.If any of those sensor becomes internally short it robs the 5 volt circuit 1 , Here a example a GMC set a EVAP code due to the fuel tank pressure sensor. Everytime the CK ENG LT came on the engine would stumble, the way the owner belived  it was a faulty fuel cap he would open the the gas cap , clear the code and everything work fine , the real fix in that case was replace the FTP sensor. The most common cause is the EOP sensor which everyone  like to ignore until there a reduce power and engine stumble.