1995 blazer rough running
 

Hello guys,
I have a 95 blazer with 200k miles on it. Recently i noticed that i get black smoke from the echaust when i hit the gas. Also the enginr shivers at low rpm or idle. When i hit the gas it goes away.
One extra thing is i feel when hitting the gas all the way a delay in response as if the car is choking.
I checked the codes i have on a scanner tool i get the iac sensor code which i changed recently (weird). My mechanic checked for any leaks from manifold gasket and there was nothing. Given that i changed spark plugs/wires and fuel sending unit with filter and air filter all together recently.

Awaiting your help thanks