Technical Misfiring on idle

[Stefanoski]

Hi everyone! I'm new here and I'd like to thank in advance anyone would try to help me!

I've got what follows:

Fiat Punto 2002 1.2 8v

a month ago we did what follows:

Headgasket
spark plugs
plug leads
coil packs
water pump
thermostat
Throttle body cleaned
coolant temp sensor
new cam belt
valves clearence checked
Injector cleaner additive
no cracks on the air system
new battery

After having done all this, the car slighly misfire on idle and consequently splutters at the back. You can tell because the engine shakes a little on idle only, regardless being cold or hot. Is not much, the rpm indicator stays still on idle, but you can hear and see the engine shaking a little.
I can make a video if needed.

On cruise is ok and responsive, easily reaching 80 mph.

I have to say that before the headgasket repairings it wasn't doing that.

I've thought about replacing the fuel pump as well, but other ppl with the same issue have done this and didn't cure it. Same thing for the ECU. we've thought about a new lambda sensor, but usually when is faulty or clogged should get the engine check light on.

I'm stuck at the moment.

Anyone in the same situation which have successfully cured this or can illuminate me on somethig else?

TIA :worship:

 

[nitramtpr]

Hmmm, that's a huge amount of work.

Initial thoughts are:

Wrong / faulty spark plugs.
Faulty plug leads.
Cam timing one tooth out.

 

[Stefanoski]

Hi nitramptr, thanks for the reply!

All three things you mentioned are new and the timing was checked even deeper and is spot on, so I'd exclude those.

Thanks again!