KingCimson

I bought a 78 280z a while back, it ran excellent until it started smoking and running rich when i step on the gas its black smoke but when its ideling its like a white or blue. Tt runs fine when its warmed up. Ive checked the injectors, changed the thermotime switch and how would i know if the cold start valve in stuck open? oil also shoots out when i take the oil cap off, could it be sticky valves?