I am having a problem with my 84 Vette when the engine is cold.IT starts quickly,but runs rough and idles terribly until it warms up. Once warm it runs very well. The car has 63 K and otherwise is in great condition. About 2 years ago,I had a major tune up, Plugs,Plug wires, filters, egr, o2 sensor, etc. Recently I have had a new fuel pump and sending unit. The electrics check out ok, as do the injectors, all sensors and the OBD shows all ok..no codes,etc. My Mechanic can't figure it out and he is excellent, and I am slowly going broke trying to find out what the problem is...Any ideas would be appreciated....Thanks