rough idle-fuel injected Spider 2000

[niro884]

Looking for any suggestions to cure some rough idling. Fuel Injected 1980 Spider 2000. RPM has been set and seems fine. Air intake boot is brand new. New Gas filter. Clean Air filter. The rough idle seems to be at start up until the car heats up. I know they like to run hot! Once it has warmed up and been driven it seems totally fine and smooth. Is this just the nature of the beast or something else? Valve clearance? Should I just leave it as is?

Thanks

[kristoj]

First thing I would suspect is the coolant temperature sensor, which is installed in the coolant tee on the front of the engine. The coolant sensor is tested on the ECU connector (under the glove box). Unplug the ECU and connect an ohmmeter between terminals 13 and ground (vehicle body). The meter should read:
7,000 to 12,000 OHMS at 14 degrees F
2,000 to 3,000 OHMS at 68 degrees F
250 to 400 OHMS at 176 degrees F

If you get different readings than those above, you probably have a bad sensor. This will cause the car to run rough when cold. I would also carefully check for vacuum leaks.

[Europa]

Look into the Auxiliary Air Regulator in addition to the coolant temp sensor. There are several posts here on the AAR and rough starting/idling on FI Spiders.

[So Cal Mark]

figure out which cylinder is misfiring, then you can find the source. Leaking head gaskets often have symptoms like you describe