Help! making headway on my sc

OK Now I can crank it when it is cold but it is hard to start and it pours black smoke out. runs good drives down the road good.After warming up it is it will not restart unless I hold the gas
wide open and pump and spin it continously then it is very rich and black smoking.Any ideas on the problem? THanks ps Anybody ever had stopped up cats?
I have replaced the fpr,iac,spark plugs,intake air temp sensor,
looks like someone has replaced the head gaskets.

I had clogged cats, boost gauge really shoots up and it is a dog when you step on it. Drives pretty good during regular driving though. It will also heat up a lot more than normal.

coolant temp sensor

Mine was doing that except it was actually harder to start when it was warm. It ended up being the coolant temperature sensor.
When it goes bad, it tells the EEC that the engine is cold so it dumps in fuel which makes it run rich and smoke.