ok first off hello all, im a newbie to this forum ,but im at my wits end
i own a seat ibiza chill 5 door 1.4 mpi 1997 i bought this car with a headgasket fault, ive had the gasket done by myself, before the car ran with old knackered headgasket it would run for about 15 seconds then on idle it would hunt untill it stalled revs dropping and going up and down..

ok with me so far ,, ive fitted new gasket , changed oil air filter and plugs ,,but same thing was happening after 15 seconds or so

,since this ive changed throttle body , o2 senor cam sensor , cambelt and new tensioner were fitted ,

also changed the fuel filter ,, got some 2nd hand injectors and fitted those

,now for the first 5 mins it ran perfect then it started again, .back to square 1 even had ecu reset

, i have to add the 02 sensor is 2nd hand and makes no difference even if its unpluged,,

but from my skills as mechanic i always thought that 02 sensor didnt start doing its thing untill car was warmed up , ? any help gladly appreciated cheers in advance paul.