Nearly at my wits end! still got a missfire!!

[RegisCup]

right, ive got to the point now where i dont know what else to check or replace and need sum advice. car is a 172 cup btw. the car has always had a very slight missfire that comes and goes but recently after having the ecu, uch etc replaced by mick its not gone away and got a little worse. (not micks fault may i add, he did a pukka job) ive so far replaced the cat, both lambdas, coil pack, leads, spark plugs, injector rail and injectors, map sensor, cleaned throttle body and tdc but the problem is still there. its not really bad but the car failed the mot last week on idle emissions, fast idle was fine. Seems strange as the last 2 years it passed with a completely knackered cat and crappy xhaust system and ive replaced the lot since then and it failed! All the bits are proper renault not cheap replacements. its just such a shame as ive spent a fortune on this car trying to get it mint and this one little thing is holding me up!! everything else is done! could it be an issue with timing? missfire is only there when warmed up and at idle, apart from that it drives spot on. any help or advice would be much appreciated

 

[MicKPM]

As per the phone call today matey, if you don't get any joy with the simple stuff drop it off and i'll fix it for you in the new year.

Mick

 

[RegisCup]

Nice 1, cudnt get hold of a coolant sensor 2day so will get 1after new year and fit it

 

[Sam@NP]

Throttle position sensor?

 

[MicKPM]

Its an electric throttle plate Sam, not got one.