Runs really bad at idle!

[ajaxajax2000]

I now had my ZR-1 '92 for 4 weeks. Since two days it has started act really weard. When I start the engine not touching the throttle it runs extreamly unevenly in a kind of slow and pulsating way. Like it's running on just half of it's cylinders. Reminds me of my old Harley (which shall run just like that at idle). Once I rev it up to 4K a couple of times it starts running normally at idle. If I don't rev the engine, but just put it in 1:st and start driving, the car feels very week and jumpy for like 10 - 20 mtrs. Then with a distinctive jolt it enters "normal" mode. When driving, the engine seems normally strong and fast.

This behaviour is the same wheter the engine is cold or hot. If I drive for one hour, stop and start, it's just the same.

Just about the time this problem started I got the "service engine soon" light on the warning display.

Any ideas, someone.

TIA

Peter