Engine not holding revs on part throttle

[RuslanA4]

Hi everyone. I've recently brought my car in for NCT and fail to pass it, they couldn't do an emissions test because engine doesn't hold revs on part throttle. When I press accelerator pedal to hold revs at @2500, it holds it only for 3-4 seconds, and after starts to rev up to 4500-5000 rpm by itself. When I release pedal the revs stay at high for few seconds and then drop down to idle. What could cause this? Scan with VCSD only shows random misfire. Any help would be greatly appreciated

[toptek]

hiya dude, had a slightly similar thing with mine, but with mine when i tried to hold steady revs, the engine would either rev high or drop to tick over, found water in the accelorator pedal, was dripping from under the ecu, had to remove pedal, took out circuit board and tracks were basically gone? had to re track it, i never got any codes up either, oh resealed ecu box. hope it helps you never know