1986 Chevy Camaro engine idles rough when cold

Engine Performance problem
1986 Chevy Camaro V8 Two Wheel Drive Automatic 130xxx miles

If the engine has been sitting long enough to cool off, it takes a lot of cranking to start it. After finally starting it lets out a big cloud of smoke out of the exhaust and idles really rough & low and will eventually die unless I give it gas until it warms, at which time it runs fine. The engine is a 305 4bbl carburated. I have changed the spark plugs, wires, replaced the egr valve. I was told it might be a bad Coolant temp sensor so I changed that but it's still acting up. Also the oil pressure will drop as the engine heats up. Not in the red but it gets close at times. I was also told this all could be due to low compression in one or more cylinders. What do you think? Ryan