Technical Rough idle

[shadow 1]

Hi All. Can you suggest where to look next to cure a erratic idle and missfire below 2500 revs. I have changed out coil packs.
replaced fuel filter. Checked plugs which were fitted recently but are black. Car pulls like a train after 2500 revs but when you release throttle at low speed then step on the gas she misfires and hick about before taking off. The car is 97 Barchetta.

 

[Bartazar]

On the early gen Barchetta I would check the idle control valve

 

[TSAF]

replace the lamba probe, with original... and problem solved..

 

[shadow 1]

Hi guys. I replaced the air control valve with new and car is the same. I removed and cleaned maf looks ok it still has the two stands on the elec part. I did change the lamba sensor recently with aftermarket part could this be the problem as its not fiat