Technical Help. high,low revving!

[tmzy]

hi my fiat punto 1.2 8v has given me no problems since i owned it but now it has and its really annoying. the engine is high low revving when i have my foot steady on the throttle but only when the engine gets warm and its not over heating. when the engine gets warm it starts to missfire and stalls my car and i can not move it again until it gets cold again.i have changed plugs and both coil packs.the ht leads are about 10 months old. any ideas as to what it could be i had a computer plugged into it with no effect
thanks
tom

 

[fingers99]

The stalling is probably TDC sensor.

The hunting idle will probably be a throttle body in need of a good clean (poundshop carb cleaner, clean the outside first).

Do a compression test too.

 

[Ziggy122]

The engine often doesn't know when the crank sensors failed, it just thinks you stalled

The up and down revs is most likely as said the Throttle body / butterfly valve ready to be cleaned up properly

Ziggy

 

[tmzy]

ok i will do it all when i get up and reply back with any news

 

[tmzy]

hi soz for late reply.was supposed to be just sorting out my car and ended up being a taxi all day lol. i cleaned the throttle body and replaced the crank sensor as i had a spare and all seems fine. i havent done a compression check yet but i will do thanks for help