Help please

[Lank]

Hello joined today hope everyones ok i have a seat leon cupra 1.8t 20v 2003 auq engine. Now i brought this car with epc light on knowing Certain things reguarding from my previous cupra 1.8t i owned so i plugged her in and had pedal a faults so got one direct feom seat at £101 and also getting rpm sensor showing up so replaced that aswel bearing in mind before i fitted anything was bearly drivable at all and hunting its head off on idle but once these 2 were fitted seemed to be better.BUT no were near what it should be so plugged her back in and had throttle body faults and noticed when igition was turn on was not setting it self so today its had that replaced brand new also no its tryon to boost and holding back at 4,500 rpm and then spits dummy and throws epc light up ignition off and on goes off same again but what i have noticed it if i put accelerater down and hold it at 4,500rpm and press and hold the brake pedal aswel as the throttle pedal its kills the engine speed and dies? Amd some times pedal aint responsive at all when epc light is on but if u press brake pedal off and on it will start working again please help!!! Sorry for story