Bad Idle and Hard Warm Starting

My car is starting to become a pain, my car seems to take a lot longer than usual to start when warm and has real bad warm idle like its missing. I have no idea what it is but i have replaced

IACV
TPS and Throttle Body
Oxygen Sensor
Spark Plugs
Ignition Leads
Coil
Distributor
Oil

I have no idea what it could be, it has been suggested it could be the ECT, but im think possibly the MAF Sensor, but i have no idea, I want the stupid car gone, this is a mystery to me and if someone could help it would be much apprecaited, i have a SR20DE U13 Nissan Bluebird